Add GuF cpuinfo and gfplatdetect

In previous releases we provided platform specific information like the board type , board revision and bootloader revision via the /proc/cpuinfo file.

Because of legacy consumers we will do a similar approach. However the population of this will be different from before: The parsing and propagation of the information should not be part of a "board-file" (residing in arch/arm/mach-imx/) but in a specific driver module. The module is called gfplatdetect.

This loosens the coupling and makes the kernel "more mainline".

However we still need some interfaces to the cpuinfo available for the module approach. This patchset introduces the necessary exports and formats the cpuinfo file as before.

It also adds the device tree entries for the gfplatdetect.