* Beaglebone cape manager driver

Required properties:
- compatible: "ti,bone-capemgr"
- eeprom: phandle to the EEPROM baseboard.
          The EEPROM framework interface is use to obtain the data.

Required children nodes:

- baseboardmaps: Contains nodes, which each of the them defines a mapping from
		 the baseboard EEPROM board-name ID to a DT friendly compatible
		 string.

  - board-name:      The baseboard EEPROM board name, i.e. A335BONE for the
                     original beaglebone white.
  - compatible-name: The DT friendly compatible string to be used for matching
		     compatible capes, i.e. "ti,beaglebone"


 - nvmem-cells: Defines the phandles of the nvmem cells of the baseboard and the
                slots.
 - nvmem-cells: Defines the names of the nvmem cells. Required to have at
                least a baseboard cell name.

 - #slots:	Defines how many slots are there.

- Example of a beaglebone cape-manager:

bone_capemgr {
	compatible = "ti,bone-capemgr";
	status = "okay";

	nvmem-cell = <&baseboard_data
		      &cape0_data &cape1_data &cape2_data &cape3_data>;
	nvmem-cell-names = "baseboard", "slot0", "slot1", "slot2", "slot3";

	#slots = <4>;

	/* map board revisions to compatible definitions */
	baseboardmaps {
		baseboard_beaglebone: board@0 {
			board-name = "A335BONE";
			compatible-name = "ti,beaglebone";
		};

		baseboard_beaglebone_black: board@1 {
			board-name = "A335BNLT";
			compatible-name = "ti,beaglebone-black";
		};
	};
};

The format of the cape to be loaded is in a standard overlay format with
the following root properties that are interpreted by the cape manager:

Required properties:
 - compatible: Should be compatible to the baseboard according to the
               baseboard map value, i.e. "ti,beaglebone".
 - part-numer: Should contain the part-number as stored in the EEPROM.
 - version:    Should contain a list of all the version that are supported
               by the single cape dtbo, i.e. "00A1".

Optional properties:
 - exclusive-use: A string list which state the resources this cape requires.
                  No processing or matching to anything regarding the internal
		  kernel state is performed; it's purpose is to guard against
		  conflicts with other capes.
 - priority:      A priority to be assigned when loading a cape. A lower value
                  has higher priority. The purpose of the priority is to control
		  which cape is loaded first in case of a conflict.

- Example of a serial cape:

/dts-v1/;
/plugin/;
/ {
        compatible = "ti,beaglebone", "ti,beaglebone-black";

        /* identification */
        part-number = "BB-BONE-SERL-03";
        version = "00A1";

        /* state the resources this cape uses */
        exclusive-use =
                /* the pin header uses */
                "P9.21",        /* uart2_txd */
                "P9.22",        /* uart2_rxd */
                /* the hardware ip uses */
                "uart2";

        fragment@0 {
                target = <&am33xx_pinmux>;
                __overlay__ {
                        bb_uart2_pins: pinmux_bb_uart2_pins {
                                pinctrl-single,pins = <
                                        0x150 0x21      /* spi0_sclk.uart2_rxd | MODE1 */
                                        0x154 0x01      /* spi0_d0.uart2_txd | MODE1 */
                                >;
                        };
                };
        };

        fragment@1 {
                target = <&uart2>;
                __overlay__ {
                        status = "okay";
                        pinctrl-names = "default";
                        pinctrl-0 = <&bb_uart2_pins>;
                };
        };
};