Add initial support for CM-T43, an AM437x based SoM.
This support includes: serial, MMC/eMMC, NAND, USB, ETH, I2C, GPIO, DRAM
detection.

Cc: Tom Rini <trini@konsulko.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>