The e500mc supports the new msgsnd/doorbell mechanisms that were added in
the Power ISA 2.05 architecture.  We use the normal level doorbell for
doing SMP IPIs at this point.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>