mtd/maps: uclinux: fix building when partition support is disabled

The uClinux map driver doesn't even use partitions, so we shouldn't require
it in order to work properly.

Signed-off-by: Timofei Bondarenko <tim@ipi.ac.ru>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
CC: Greg Ungerer <gerg@uclinux.org>
CC: uclinux-dev@uclinux.org
CC: linux-mtd@lists.infradead.org
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>