s390/zcore: no need to check return value of debugfs_create functions

[ Upstream commit 7449ca87 ]

When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

See commit 7dd541a3 ("s390: no need to check return value of debugfs_create functions").

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Stable-dep-of: 0b18c852 ("tracing: Have saved_cmdlines arrays all in one allocation")
Signed-off-by: Sasha Levin <sashal@kernel.org>