i2c: allow configuration of imx driver for ColdFire architecture

The i2c controller used by Freescales iMX processors is the same
hardware module used on Freescales ColdFire family of processors.

We can use the existing i2c-imx driver on ColdFire family members.
Modify the configuration to allow it to be selected when compiling
for ColdFire targets.

Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>