MAINTAINERS: Exclude m68k-only drivers from powerpc entry

The powerpc section has a "F:" entry for drivers/macintosh, matching all
files in or below drivers/macintosh. That is correct for the most part,
but there are a couple of m68k-only drivers in the directory, so exclude
those.
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230531125023.1121060-1-mpe@ellerman.id.au

MAINTAINERS

@@ -11912,6 +11912,8 @@ L:	linuxppc-dev@lists.ozlabs.org
 S:	Odd Fixes
 F:	arch/powerpc/platforms/powermac/
 F:	drivers/macintosh/
+X:	drivers/macintosh/adb-iop.c
+X:	drivers/macintosh/via-macii.c
 
 LINUX FOR POWERPC (32-BIT AND 64-BIT)
 M:	Michael Ellerman <mpe@ellerman.id.au>