target-ppc: Don't share get_pteg_offset() between 32 and 64-bit

target-ppc: Don't share get_pteg_offset() between 32 and 64-bit

The get_pteg_offset() helper function is currently shared between 32-bit
and 64-bit hash mmus, taking a parameter for the hash pte size.  In the
64-bit paths, it's only called in one place, and it's a trivial
calculation.  This patch, therefore, open codes it for 64-bit.  The
remaining version, which is used in two places is made 32-bit only and
moved to mmu-hash32.c.

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