This patch adds basic support for the mx28-evk board. Debug UART, MMC and FEC
have been successfully used.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

MMU now can be enabled on every ARM board, so remove
the dependency.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

We never supported the sigmatel stm chips and probably
never will. So do the first step and rename the architecture
to mxs just like in the kernel.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>