ARM: imx: Add 2 GiB DRAM support for DH electronics i.MX8M Plus DHCOM

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>
diff --git a/board/dhelectronics/dh_imx8mp/Makefile b/board/dhelectronics/dh_imx8mp/Makefile
index 86ffc31..e5a29fd 100644
--- a/board/dhelectronics/dh_imx8mp/Makefile
+++ b/board/dhelectronics/dh_imx8mp/Makefile
@@ -5,7 +5,7 @@
 #
 
 ifdef CONFIG_SPL_BUILD
-obj-y += spl.o lpddr4_timing_4G_32.o
+obj-y += spl.o lpddr4_timing_2G_32.o lpddr4_timing_4G_32.o
 else
 obj-y += imx8mp_dhcom_pdk2.o
 endif