KVM: PPC: BookE: Handle alignment interrupts

When the guest triggers an alignment interrupt, we don't handle it properly
today and instead BUG_ON(). This really shouldn't happen.

Instead, we should just pass the interrupt back into the guest so it can deal
with it.

Reported-by: Gao Guanhua-B22826 <B22826@freescale.com>
Tested-by: Gao Guanhua-B22826 <B22826@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>