feat(imx8m): update the ddr4 dvfs flow to include ddr3l support

the DDR3L & DDR4 can share same piece of code for DDR frequency scaling.
So update the ddr4 dvfs flow to support DDR3L too.

Signed-off-by: Jacky Bai <ping.bai@nxp.com>
Reviewed-by: Anson Huang <anson.huang@nxp.com>
Change-Id: Ifc6981f05ed8a4e399adad97690197a9680f554d
2 files changed