KVM: PPC: Book3S: Move skip-interrupt handlers to common code

Both PR and HV KVM have separate, identical copies of the
kvmppc_skip_interrupt and kvmppc_skip_Hinterrupt handlers that are
used for the situation where an interrupt happens when loading the
instruction that caused an exit from the guest.  To eliminate this
duplication and make it easier to compile in both PR and HV KVM,
this moves this code to arch/powerpc/kernel/exceptions-64s.S along
with other kernel interrupt handler code.

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