powerpc/86xx: Correct reading of information presented in cpuinfo

/proc/cpuinfo should be showing the boards revision and the revision of
the FPGA fitted. The functions currently used to access this information
as incorrect.

Additionally the VME geographical address of the PPC9A and it's status as
system contoller are available in the board registers. Show these in
cpuinfo.

Signed-off-by: Martyn Welch <martyn.welch@gefanuc.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>