target/ppc: Remove interrupt handler wrapper functions

target/ppc: Remove interrupt handler wrapper functions

These wrappers call out to handle POWER7 and newer in separate
functions but reduce to the generic case when TARGET_PPC64 is not
defined. It is easy enough to include the switch in the beginning of
the generic functions to branch out to the specific functions and get
rid of these wrappers. This avoids one indirection and entirely
compiles out the switch without TARGET_PPC64.

Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>