Add basic support for the DENX M53EVK board. Currently supported is:
MMC (incl. booting)
NAND (incl. booting)
Ethernet, I2C, USB, SATA, RTC.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Albert ARIBAUD <albert.u.boot@aribaud.net>
Cc: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Tom Rini <trini@ti.com>
Cc: Wolfgang Denk <wd@denx.de>