Generic on-chip SRAM

Simple IO memory regions to be managed by the genalloc API.

Required properties:

- compatible : "mmio-sram" for generic SRAM, or
               "brcm,boot-sram" for the boot SRAM on Broadcom SoCs

- reg : SRAM iomem address range

Example:

sram: sram@5c000000 {
	compatible = "mmio-sram";
	reg = <0x5c000000 0x40000>; /* 256 KiB SRAM at address 0x5c000000 */
};