target-ppc: Disentangle pte_check()

target-ppc: Disentangle pte_check()

Currently support for both 32-bit and 64-bit hash MMUs share an
implementation of pte_check.  But there are enough differences that this
means the shared function has several very ugly conditionals on "is_64b".

This patch cleans things up by separating out the 64-bit version
(putting it into mmu-hash64.c) and the 32-bit hash version (putting it
in mmu-hash32.c).  Another copy remains in mmu_helper.c, which is used
for the 6xx software loaded TLB paths.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>