arm: imx: add i.MX6SLL EVK board support

Add i.MX6SLL EVK board support.
1. Add imx6sll-evk device tree.
2. Enable SDHC/I2C/UART.
3. Enable REGULATOR/PMIC/I2C/GPIO/SDHC/PINCTRL driver.

Boot Log:
U-Boot 2016.11-00127-gc635871-dirty (Nov 24 2016 - 13:28:19 +0800)

CPU:   Freescale i.MX6SLL rev1.0 at 792MHz
CPU:   Commercial temperature grade (0C to 95C)Reset cause: POR
Model: Freescale i.MX6SLL EVK Board
Board: MX6SLL EVK
DRAM:  2 GiB
i2c bus 0 at 35258368, no gpio pinctrl state.
PMIC: PFUZE100! DEV_ID=0x10 REV_ID=0x21
MMC:   FSL_SDHC: 0, FSL_SDHC: 1, FSL_SDHC: 2
In:    serial
Out:   serial
Err:   serial
Net:   CPU Net Initialization Failed
No ethernet found.
Hit any key to stop autoboot:  0

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
diff --git a/configs/mx6sllevk_defconfig b/configs/mx6sllevk_defconfig
new file mode 100644
index 0000000..8ae049e
--- /dev/null
+++ b/configs/mx6sllevk_defconfig
@@ -0,0 +1,36 @@
+CONFIG_ARM=y
+CONFIG_ARCH_MX6=y
+CONFIG_TARGET_MX6SLLEVK=y
+CONFIG_DEFAULT_DEVICE_TREE="imx6sll-evk"
+CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/freescale/mx6sllevk/imximage.cfg"
+CONFIG_BOOTDELAY=3
+CONFIG_HUSH_PARSER=y
+CONFIG_CMD_BOOTZ=y
+# CONFIG_CMD_IMLS is not set
+CONFIG_CMD_MEMTEST=y
+CONFIG_CMD_MMC=y
+CONFIG_CMD_I2C=y
+CONFIG_CMD_GPIO=y
+CONFIG_CMD_DHCP=y
+CONFIG_CMD_PING=y
+CONFIG_CMD_CACHE=y
+CONFIG_CMD_REGULATOR=y
+CONFIG_CMD_EXT2=y
+CONFIG_CMD_EXT4=y
+CONFIG_CMD_EXT4_WRITE=y
+CONFIG_CMD_FAT=y
+CONFIG_CMD_FS_GENERIC=y
+CONFIG_OF_CONTROL=y
+# CONFIG_BLK is not set
+CONFIG_DM_GPIO=y
+CONFIG_DM_I2C=y
+CONFIG_DM_MMC=y
+# CONFIG_DM_MMC_OPS is not set
+CONFIG_PINCTRL=y
+CONFIG_PINCTRL_IMX6=y
+CONFIG_DM_PMIC=y
+CONFIG_DM_PMIC_PFUZE100=y
+CONFIG_DM_REGULATOR=y
+CONFIG_DM_REGULATOR_PFUZE100=y
+CONFIG_DM_REGULATOR_FIXED=y
+CONFIG_DM_REGULATOR_GPIO=y