mtd: allow uclinux map driver to be used on any ColdFire CPU platform

The uclinux.c map driver has traditionally been used only on non-MMU based
systems. But there is no fundamental reason it can't be used on systems
running with virtual memory.

Some ColdFire CPU based systems now have full paged MMU hardware and can use
the uclinux.c mapping driver, so making the uclinux.c driver configuration
depend on !CONFIG_MMU doesn't make sense now. Allow the CONFIG_MTD_UCLINUX
option to be enabled if CONFIG_COLDFIRE is enabled. (I have chosen not to
just more generally allow uclinux.c for any MMU type to keep this option
hidden for most systems that are not interested in setting it).

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>