KVM: PPC: Book3S PR: Don't keep scanning HPTEG after we find a match

The loop in kvmppc_mmu_book3s_64_xlate() that looks up a translation
in the guest hashed page table (HPT) keeps going if it finds an
HPTE that matches but doesn't allow access.  This is incorrect; it
is different from what the hardware does, and there should never be
more than one matching HPTE anyway.  This fixes it to stop when any
matching HPTE is found.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>