m68k: atari_keyb_init operator precedence fix

Fix operator precedence bug in atari_keyb_init, which caused a failure on CT60

Signed-off-by: Michael Schmitz <schmitz@debian.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>