MA-14981-3 Add evk_imx8mm 4GB DDR support

Add new target to build evk_imx8mm 4GB DDR board, the
TEE should be moved to 0xfe00_0000.

Change-Id: If0e5385bd009d5ca2c194961b3f594586f399d27
Signed-off-by: Ji Luo <ji.luo@nxp.com>

iMX8M/soc.mak

@@ -25,7 +25,7 @@ PLAT = imx8mm
 HDMI = no
 SPL_LOAD_ADDR = 0x7E1000
 SPL_FSPI_LOAD_ADDR = 0x7E2000
-TEE_LOAD_ADDR = 0xbe000000
+TEE_LOAD_ADDR ?= 0xbe000000
 ATF_LOAD_ADDR = 0x00920000
 VAL_BOARD = val
 #define the F(Q)SPI header file