s390/pkey: Wipe sensitive data on failure

[ Upstream commit 1d8c270de5eb74245d72325d285894a577a945d9 ]

Wipe sensitive data from stack also if the copy_to_user() fails.

Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Ingo Franzki <ifranzki@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 6e2e374403bf73140d0efc9541cb1b3bea55ac02)
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>