uboot-imx

armv8/fsl-lsch3: Add support for second DDR clock

FSL-LSCH3 platforms can have multiple DDR clocks. LS2085A has one clock for
general DDR controlers, and another clock for DP-DDR. DDR driver needs to
change to support multiple clocks.

Signed-off-by: York Sun <yorksun@freescale.com>