Texas Instruments TI-SCI Clocks

All clocks on Texas Instruments' SoCs that contain a System Controller
core, are only controlled by this entity. Communication between a
host processor running an OS and the System Controller happens through a
protocol known as TI SCI. This clock implementation plugs into the
common clock framework and makes use of the TI SCI protocol on clock
API requests.

Required properties:
- compatible: Must be "ti,sci-clk"
- #clock-cells: Shall be 2.
  In clock consumers, this cell represents the device ID and clock ID
  exposed by the PM firmware. The assignments can be found in the header
  files <dt-bindings/genpd/<soc>.h> (which covers the device IDs) and
  <dt-bindings/clock/<soc>.h> (which covers the clock IDs), where <soc>
  is the SoC involved, for example 'k2g'.
- ti,sci: Phandle to the TI SCI device to use for managing the clocks

Optional properties:
- ti,ssc-clocks: Array of phandle clocks that shall enable spread spectrum
		 clocking while enabled
- ti,allow-freq-change-clocks: Array of phandle clocks that shall allow
			       dynamic clock frequency changes by firmware
- ti,input-term-clocks: Array of phandle clocks that shall enable input
			termination

Examples:

k2g_clks: k2g_clks {
	compatible = "ti,sci-clk";
	ti,sci = <&pmmc>;
	#clock-cells = <2>;
};

dummy_node@1234 {
	clocks = <&k2g_clks K2G_DEV_DUMMY K2G_DEV_DUMMY_FCK>;
};

dummy_node2@2345 {
	clocks = <&k2g_clks K2G_DEV_DUMMY2 K2G_DEV_DUMMY_X1_CLK>;
};

&k2g_clks {
	ti,ssc-clocks = <&k2g_clks K2G_DEV_DUMMY K2G_DEV_DUMMY_FCK>;
};