KVM: PPC: BookE: fix sleep with interrupts disabled

It is not legal to call mutex_lock() with interrupts disabled.
This will assert with debug checks enabled.

If there's a real need to disable interrupts here, it could be done
after the mutex is acquired -- but I don't see why it's needed at all.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Reviewed-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>