Provide an unregister interface for the opal message notifiers
to be called when not needed like during driver unload/remove.
Signed-off-by: NNeelesh Gupta <neelegup@linux.vnet.ibm.com>
Reviewed-by: NVasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>