MLK-20044 plat: imx8m: fix ddr4 dvfs hang after retention

The RFSHCTL3.refresh_mode should be set normal mode if we
want to disable auto refresh mode.

Signed-off-by: Bai Ping <ping.bai@nxp.com>
(cherry picked from commit 7a2af8801053c087cd0f3a29ac505f4b482933a4)
1 file changed