imx: Add SeeedStudio NPI-IMX6ULL Support

CPU:   Freescale i.MX6ULL rev1.1 792 MHz (running at 396 MHz)
CPU:   Industrial temperature grade (-40C to 105C) at 49C
Reset cause: POR
Model: Seeed NPi iMX6ULL Dev Board with NAND
Board: Seeed NPi i.MX6ULL Dev Board
DRAM:  512 MiB
NAND:  512 MiB
MMC:   FSL_SDHC: 0
In:    serial@2020000
Out:   serial@2020000
Err:   serial@2020000
Net:   FEC0

Working:
- Eth0
- MMC/SD
- NAND
- UART 1
- USB host

Signed-off-by: Navin Sankar Velliangiri <navin@linumiz.com>

Note:

Changes in v2:

 * removed unnecessary space in imx6ull-seeed-npi-imx6ull-dev-board.dts file.
 * Used SZ_2M for CONFIG_SYS_MALLOC_LEN size allocation.
diff --git a/board/seeed/npi_imx6ull/README b/board/seeed/npi_imx6ull/README
new file mode 100644
index 0000000..01d218a
--- /dev/null
+++ b/board/seeed/npi_imx6ull/README
@@ -0,0 +1,61 @@
+How to use U-BOOT on SeeedStudio NPI-IMX6ULL Single Board Computer
+------------------------------------------------------------------
+
+- Configure and build U-Boot for NPI-IMX6ULL:
+
+    $ export ARCH=arm
+    $ export CROSS_COMPILE=arm-none-linux-gnueabihf-
+    $ make seeed_npi_imx6ull_defconfig
+    $ make
+
+This will generate SPL and u-boot-dtb.img images.
+
+Boot from MMC/SD:
+- The SPL and u-boot-dtb.img images need to be flashed into the micro SD card:
+
+    $ sudo dd if=SPL of=/dev/mmcblk0 bs=1k seek=1; sync
+    $ sudo dd if=u-boot-dtb.img of=/dev/mmcblk0 bs=1k seek=69; sync
+
+- Boot mode settings:
+
+  Boot switch position: SW1 -> 0
+			SW2 -> 1
+			SW3 -> 0
+			SW4 -> 0
+			SW5 -> 1
+			SW6 -> 0
+			SW7 -> 0
+			SW8 -> 1
+
+Boot from NAND:
+- Boot the board using SD/MMC or Serial download and load the SPL into memory
+either from SD/MMC or TFTP.
+
+Default MTD layout is 512k(spl),1m(uboot),1m(uboot-dup),-(ubi)
+
+Flash SPL to NAND from SD/MMC,
+
+    $ ext4load mmc 0:2 $loadaddr SPL
+    $ nand erase.part spl
+    $ nandbcb init $loadaddr 0x0 $filesize
+
+Flash u-boot image to NAND from SD/MMC,
+
+    $ ext4load mmc 0:2 $loadaddr u-boot-dtb.img
+    $ nand erase.part uboot
+    $ nand write $loadaddr uboot $filesize
+
+- Boot mode settings:
+
+  Boot switch position: SW1 -> 0
+			SW2 -> 1
+			SW3 -> 1
+			SW4 -> 0
+			SW5 -> 0
+			SW6 -> 1
+			SW7 -> 0
+			SW8 -> 0
+
+- Connect the Serial cable to UART0 and the PC for the console.
+
+- Reset the board using reset button and U-Boot should boot from NAND.