Add iMX8ULP DDR initialization driver which loads the DDR timing parameters and executes the training procedure. When enabling IMX8ULP_DRAM_PHY_PLL_BYPASS, using PHY PLL bypass mode to do DDR init Signed-off-by: Ye Li <ye.li@nxp.com>
Introduce DDR driver for i.MX8M. The driver will be used by SPL to initialze DDR PHY and DDR Controller. Signed-off-by: Peng Fan <peng.fan@nxp.com>