KVM: PPC: Remove shared defines for SPE and AltiVec interrupts

We currently decide at compile-time which of the SPE or AltiVec units to
support exclusively. Guard kernel defines with CONFIG_SPE_POSSIBLE and
CONFIG_PPC_E500MC and remove shared defines.

Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>