mmu-hash*: Separate PTEG searching from permissions checking

find_pte{32,64{() do several things.  First they search through a PTEG
ooking for a PTE matching our virtual address.  Then they do permissions
checking and other processing on that PTE.

This patch separates the search by VA out from the rest.  The search is
combined with the pte{32,64}_match() functions into new
ppc_has{32,64}_pteg_search() functions.

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