target-ppc: Disentangle BAT code for 32-bit hash MMUs

target-ppc: Disentangle BAT code for 32-bit hash MMUs

The functions for looking up BATs (Block Address Translation - essentially
a level 0 TLB) are shared between the classic 32-bit hash MMUs and the
6xx style software loaded TLB implementations.

This patch splits out a copy for the 32-bit hash MMUs, to facilitate
cleaning it up.  The remaining version is left, but cleaned up slightly
to no longer deal with PowerPC 601 peculiarities (601 has a hash MMU).

Signed-off-by: David Gibson <[email protected]>
Signed-off-by: Alexander Graf <[email protected]>