s390/zcrypt: fix memleak at release

commit 388bb19b upstream.

If a process is interrupted while accessing the crypto device and the
global ap_perms_mutex is contented, release() could return early and
fail to free related resources.

Fixes: 00fab235 ("s390/zcrypt: multiple zcrypt device nodes support")
Cc: <stable@vger.kernel.org> # 4.19
Cc: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>