Broadcom GISB bus Arbiter controller

Required properties:

- compatible: should be "brcm,gisb-arb"
- reg: specifies the base physical address and size of the registers
- interrupt-parent: specifies the phandle to the parent interrupt controller
  this arbiter gets interrupt line from
- interrupts: specifies the two interrupts (timeout and TEA) to be used from
  the parent interrupt controller

Optional properties:

- brcm,gisb-arb-master-mask: 32-bits wide bitmask used to specify which GISB
  masters are valid at the system level
- brcm,gisb-arb-master-names: string list of the litteral name of the GISB
  masters. Should match the number of bits set in brcm,gisb-master-mask

Example:

gisb-arb@f0400000 {
	compatible = "brcm,gisb-arb";
	reg = <0xf0400000 0x800>;
	interrupts = <0>, <2>;
	interrupt-parent = <&sun_l2_intc>;

	brcm,gisb-arb-master-mask = <0x7>;
	brcm,gisb-arb-master-names = "bsp_0", "scpu_0", "cpu_0";
};