m68k: macide doesnt check for Mac

The Macintosh IDE driver (macide) doesn't check whether it's actually running
on Mac hardware, causing a crash if it isn't.

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