linux: Amend upstream patch to harden mount points of /dev

linux: Amend upstream patch to harden mount points of /dev

This patch, which has been merged into the mainline Linux kernel, but
not yet backported to the 5.15.x tree, precisely addresses our
situation: IPFire does not use systemd, but CONFIG_DEVTMPFS_MOUNT.

The only explanation I have for bug #12889 arising _now_ is that some
component (dracut, maybe) changed its behaviour regarding remounting of
already mounted special file systems. As current dracut won't (re)mount
any file system already found to be mounted, this means that the mount
options decided by the kernel remained untouched for /dev, hence being
weak in terms of options hardening possible.

As CONFIG_DEVTMPFS_SAFE would not show up in "make menuconfig", changes
to kernel configurations have been simulated.

Fixes: #12889
Cc: Michael Tremer <michael.tremer@ipfire.org>
Signed-off-by: Peter Müller <peter.mueller@ipfire.org>