pico-imx7d: Add initial support

Add the initial support for pico-imx7d board based on Wig Cheng's
source code.

Add support for eMMC, USB gadget, I2C, PMIC and Ethernet.

For more information about this board, please visit:
http://www.technexion.org/products/pico/pico-som/pico-imx7-emmc

Signed-off-by: Vanessa Maegima <vanessa.maegima@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>

configs/pico-imx7d_defconfig

@@ -0,0 +1,35 @@
+CONFIG_ARM=y
+CONFIG_ARCH_MX7=y
+CONFIG_TARGET_PICO_IMX7D=y
+CONFIG_IMX_RDC=y
+CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/technexion/pico-imx7d/imximage.cfg"
+CONFIG_HUSH_PARSER=y
+CONFIG_CMD_BOOTZ=y
+# CONFIG_CMD_BOOTD is not set
+# CONFIG_CMD_IMI is not set
+# CONFIG_CMD_IMLS is not set
+# CONFIG_CMD_XIMG is not set
+# CONFIG_CMD_SETEXPR is not set
+CONFIG_CMD_MMC=y
+CONFIG_CMD_PART=y
+CONFIG_CMD_I2C=y
+CONFIG_CMD_GPIO=y
+CONFIG_CMD_DHCP=y
+CONFIG_CMD_CACHE=y
+CONFIG_CMD_EXT2=y
+CONFIG_CMD_EXT4=y
+CONFIG_CMD_EXT4_WRITE=y
+CONFIG_CMD_FAT=y
+CONFIG_CMD_USB=y
+CONFIG_CMD_USB_MASS_STORAGE=y
+CONFIG_USB=y
+CONFIG_USB_EHCI_HCD=y
+CONFIG_MXC_USB_OTG_HACTIVE=y
+CONFIG_USB_STORAGE=y
+CONFIG_USB_GADGET=y
+CONFIG_CI_UDC=y
+CONFIG_USB_GADGET_DOWNLOAD=y
+CONFIG_G_DNL_MANUFACTURER="FSL"
+CONFIG_G_DNL_VENDOR_NUM=0x0525
+CONFIG_G_DNL_PRODUCT_NUM=0xa4a5
+CONFIG_OF_LIBFDT=y