MLK-23574-27 imx8mm_evk: Update board codes and add DDR4 support

Update the board codes to use latest DDR script and support flexspi boot,
USB host/gadget, etc.
Also add DDR4 EVK board support for RAW NAND boot.

Signed-off-by: Ye Li <ye.li@nxp.com>
(cherry picked from commit 07c35f4)
(cherry picked from commit 85e00a8)

Author: Ye Li

arch/arm/mach-imx/imx8m/Kconfig

@@ -59,6 +59,12 @@ config TARGET_IMX8MM_EVK
 	select ARCH_MISC_INIT
 	select SPL_CRYPTO if SPL
 
+config TARGET_IMX8MM_DDR4_EVK
+	bool "imx8mm DDR4 EVK board"
+	select IMX8MM
+	select SUPPORT_SPL
+	select IMX8M_DDR4
+
 config TARGET_IMX8MM_ICORE_MX8MM
 	bool "Engicam i.Core MX8M Mini SOM"
 	select IMX8MM

board/freescale/imx8mm_evk/Kconfig

@@ -1,4 +1,4 @@
-if TARGET_IMX8MM_EVK
+if TARGET_IMX8MM_EVK || TARGET_IMX8MM_DDR4_EVK
 
 config SYS_BOARD
 	default "imx8mm_evk"
@@ -10,6 +10,8 @@ config SYS_CONFIG_NAME
 	default "imx8mm_evk"
 
 config IMX_CONFIG
-	default "board/freescale/imx8mm_evk/imximage-8mm-lpddr4.cfg"
+	default "board/freescale/imx8mm_evk/imximage-8mm.cfg"
+
+source "board/freescale/common/Kconfig"
 
 endif

board/freescale/imx8mm_evk/Makefile

@@ -9,4 +9,5 @@ obj-y += imx8mm_evk.o
 ifdef CONFIG_SPL_BUILD
 obj-y += spl.o
 obj-$(CONFIG_IMX8M_LPDDR4) += lpddr4_timing.o
+obj-$(CONFIG_IMX8M_DDR4) += ddr4_timing.o
 endif