[POWERPC] Add CONFIG_PPC_PSERIES_DEBUG to enable debugging for platforms/pseries

Add a DEBUG config setting which turns on all (most) of the debugging
under platforms/pseries.

To have this take effect we need to remove all the #undef DEBUG's, in
various files. We leave the #undef DEBUG in platforms/pseries/lpar.c,
as this enables debugging printks from the low-level hash table routines,
and tends to make your system unusable. If you want those enabled you
still have to turn them on by hand.

Also some of the RAS code has a DEBUG block which causes a functional
change, so I've keyed this off a different (non-existant) debug #define.

This is only enabled if you have PPC_EARLY_DEBUG enabled also.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>