Refine the ddr init driver to make it more reusable for different
DDR type(LPDDR4, DDR4 & DDR3L). So we can reduce some redundant
code.
Signed-off-by: NJacky Bai <ping.bai@nxp.com>
Reviewed-by: NYe Li <ye.li@nxp.com>
Signed-off-by: NPeng Fan <peng.fan@nxp.com>