The DH electronics i.MX8M Plus DHCOM SoM currently supports only 4 GiB
of DRAM population option. Add another population option with 2 GiB of
DRAM. The chips used on the 2 GiB option are 2x K4F6E3S4HM-MGCJ .
Signed-off-by: Marek Vasut <marex@denx.de>