imx: Add i.MX8MM EVK board support.

Add board and SoC dts
Add ddr training code
support SD/MMC/GPIO/PINCTRL/UART

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index 7a0b05b..2c86b29 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -641,7 +641,8 @@
 	fsl-imx8qxp-colibri.dtb \
 	fsl-imx8qxp-mek.dtb
 
-dtb-$(CONFIG_ARCH_IMX8M) += fsl-imx8mq-evk.dtb
+dtb-$(CONFIG_ARCH_IMX8M) += fsl-imx8mq-evk.dtb \
+	imx8mm-evk.dtb
 
 dtb-$(CONFIG_RCAR_GEN2) += \
 	r8a7790-lager-u-boot.dtb \