Motion-PRO: Add setting of SDelay reg. to SDRAM controller configuration.

Per AN3221 (MPC5200B SDRAM Initialization and Configuration), the SDelay
register must be written a value of 0x00000004 as the first step of the
SDRAM contorller configuration.

Signed-off-by: Bartlomiej Sieka <tur@semihalf.com>