Documentation: dt: Update ti,emif bindings

  the value shall be "emif<n>" where <n> is the number of the EMIF

  instance with base 1.

Required only for "ti,emif-am3352" and "ti,emif-am4372":

- sram			: Phandles for generic sram driver nodes,

  first should be type 'protect-exec' for the driver to use to copy

  and run PM functions, second should be regular pool to be used for

  data region for code. See Documentation/devicetree/bindings/sram/sram.txt

  for more details.

Optional properties:

- cs1-used		: Have this property if CS1 of this EMIF

  instance has a memory part attached to it. If there is a memory

- hw-caps-temp-alert	: Have this property if the controller

  has capability for generating SDRAM temperature alerts

Example:

-Examples:

emif1: emif@0x4c000000 {

	compatible	= "ti,emif-4d";

	hw-caps-ll-interface;

	hw-caps-temp-alert;

};

/* From am33xx.dtsi */

emif: emif@4c000000 {

        compatible = "ti,emif-am3352";

        reg =   <0x4C000000 0x1000>;

        sram = <&pm_sram_code

                &pm_sram_data>;

};