misc: mic/scif: re-take a lock on error path

The caller expects that we take this lock again before returning
otherwise it you get double unlocks and races.

Fixes: ba612aa8 ('misc: mic: SCIF memory registration and unregistration')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>