s390/ipl: add missing secure/has_secure file to ipl type 'unknown'

stable inclusion
from stable-v5.10.195
commit 54d03dc5d1c385bd7ba2dbd9fc3a83d2f280eaad
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I95JOC

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=54d03dc5d1c385bd7ba2dbd9fc3a83d2f280eaad



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commit ea5717cb upstream.

OS installers are relying on /sys/firmware/ipl/has_secure to be
present on machines supporting secure boot. This file is present
for all IPL types, but not the unknown type, which prevents a secure
installation when an LPAR is booted in HMC via FTP(s), because
this is an unknown IPL type in linux. While at it, also add the secure
file.

Fixes: c9896acc ("s390/ipl: Provide has_secure sysfs attribute")
Cc: stable@vger.kernel.org
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>