Commit 6ef4716c cleaned up parsing of -boot option argument, but
accidentally dropped parameter strict.  It should have been updated
exactly like parameter menu. Do that.

Signed-off-by: Amos Kong <akong@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>