UBUNTU: SAUCE: (efi-lockdown) Really don't allow lifting lockdown from userspace

UBUNTU: SAUCE: (efi-lockdown) Really don't allow lifting lockdown from userspace

BugLink: https://bugs.launchpad.net/bugs/1851380
"UBUNTU: SAUCE: (efi-lockdown) Add a SysRq option to lift kernel
lockdown" adds a sysrq key to lift kernel lockdown, which is
meant to only allow a physically present user to lift lockdown
using a keyboard. However, the code has a bug which also allows
root to lift lockdown through /proc/sysrq-trigger. Fix this bug
to make this work as intended.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Connor Kuehl <connor.kuehl@canonical.com>
Acked-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>