The use of the DDR driver as well as early I2C support is
enabled for board initialising their memory through SPD EEPROM
data.
A SOC specific function returning the DDR bus frequency
is added for the DDR driver to translate DDR timings to
register values.
Signed-off-by: Renaud Barbier <renaud.barbier@ge.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>