XXX mpic: add locks
KVM: PPC: MPIC: Add support for KVM_IRQ_LINE

Now that all pieces are in place for reusing generic irq infrastructure,
we can copy x86's implementation of KVM_IRQ_LINE irq injection and simply
reuse it for PPC, as it will work there just as well.

Signed-off-by: Alexander Graf <agraf@suse.de>