p1014rdb: set ddr bus width properly depending on SVR

Currently, for NAND boot for the P1010/4RDB we hard code the DDR
configuration. We can still dynamically set the DDR bus width in
the nand spl so the P1010/4RDB boards can boot from the same
u-boot image

Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>