target/ppc/mmu_common.c: Remove nx field from mmu_ctx_t

Pass it as a parameter instead. Also use named constants instead of
hex values when extracting bits from SR.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
1 file changed