m68k : Kill CONFIG_MTD_PARTITIONS

This patch removes CONFIG_MTD_PARTITIONS in config files for m68k.
Because CONFIG_MTD_PARTITIONS was removed by commit 6a8a98b2.

Signed-off-by: Eunbong Song <eunb.song@samsung.com>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>