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/board/freescale/imx8mm_evk/Kconfig b/board/freescale/imx8mm_evk/Kconfig
new file mode 100644
index 0000000..299691a
--- /dev/null
+++ b/board/freescale/imx8mm_evk/Kconfig
@@ -0,0 +1,12 @@
+if TARGET_IMX8MM_EVK
+
+config SYS_BOARD
+	default "imx8mm_evk"
+
+config SYS_VENDOR
+	default "freescale"
+
+config SYS_CONFIG_NAME
+	default "imx8mm_evk"
+
+endif