Flash device on ARM Versatile board

These flash chips are found in the ARM reference designs like Integrator,
Versatile, RealView, Versatile Express etc.

They are regular CFI compatible (Intel or AMD extended) flash chips with
some special write protect/VPP bits that can be controlled by the machine's
system controller.

Required properties:
- compatible : must be "arm,versatile-flash", "cfi-flash";
- reg : memory address for the flash chip
- bank-width : width in bytes of flash interface.

For the rest of the properties, see mtd-physmap.txt.

The device tree may optionally contain sub-nodes describing partitions of the
address space. See partition.txt for more detail.

Example:

flash@34000000 {
	compatible = "arm,versatile-flash", "cfi-flash";
	reg = <0x34000000 0x4000000>;
	bank-width = <4>;
};