m68k: mac: Remove misleading comment

This code path was tested on a Quadra 950 a long time ago and the
comment isn't needed.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Cc: Joshua Thompson <funaho@jurai.org>
Link: https://lore.kernel.org/r/10dff3e7c17d363a4b239aae7b3ebab32bef3547.1589949122.git.fthain@telegraphics.com.au


Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>