uboot-imx

MLK-21821 ddr: imx8m: Fix the ddr init hang on imx8mq

On, i.MX8MQ, the PLL config must be done when ddrmix
isolation is released. So move the dram pll init after
iso config done. For other i.MX8M SOC, either init pll
before or after isolation is ok.

Signed-off-by: Jacky Bai <ping.bai@nxp.com>
(cherry picked from commit c5dcc21c214badd5b48b48dfaa62d17ba13c6b17)