powerpc/kernel/sysfs: Cleanup set up macros for PMC/non-PMC SPRs

Currently PMC (Performance Monitor Counter) setup macros are used
for other SPRs. Since not all SPRs are PMC related, this patch
modifies the exisiting macro and uses it to setup both PMC and
non PMC SPRs accordingly.

Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>