m68k: Prefix ISA type with ISA_TYPE_

The *_ISA type defines are quite generic and cause namespace conflicts
(e.g. with `AMIGAHW_DECLARE(GG2_ISA)' in <asm/amigahw.h>) for some kernel
configurations. Use ISA_TYPE_* to avoid such conflicts.

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