m68k/mac: cleanup macro case

Code style convention has macro names in uppercase. Change MAC_VIA_IIci to MAC_VIA_IICI.

Also remove an obsolete comment.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>