driver: ddr: imx: correct the pwrctl setting of selfref_en on imx8m

The 'selfref_en' should be bit'0', so correct the setting to
enable the auto self-refresh.

Reviewed-by: Jian Li <jian.li@nxp.com>
Reviewed-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Jacky Bai <ping.bai@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
1 file changed