vt: add permission check for KDSKBMETA ioctl

vt: add permission check for KDSKBMETA ioctl

KDSKBMETA modifies keyboard meta mode but lacks the !perm check that all
other keyboard setter ioctls in vt_k_ioctl() enforce, allowing a process
to change meta mode on a non-controlling console without authorization.

Assisted-by: AISLE:Snapshot
Cc: stable <stable@kernel.org>
Signed-off-by: Joshua Rogers <linux@joshua.hu>
Link: https://patch.msgid.link/20260731-tty-vt-stuff-v1-2-be99b9da8e30@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>