This shoud fix the problem with SysRq mode staying half-way enabled
and interfereing with normal PrtScrn operation after user presses ALT
for the first time.
Reported-and-tested-by: NÉric Piel <E.A.B.Piel@tudelft.nl>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>