imx6: isiotmx6ul: Add I2C support

Add I2C support for Engicam Is.IoT MX6UL module.

isiotmx6ul> i2c bus
Bus 0:  i2c@021a0000
Bus 1:  i2c@021a4000
isiotmx6ul> i2c dev 0
Setting bus to 0
isiotmx6ul> i2c dev
Current bus is 0
isiotmx6ul> i2c speed 100000
Setting bus speed to 100000 Hz
isiotmx6ul> i2c probe
Valid chip addresses: 00 2C 44 78
isiotmx6ul> i2c md 2C 0xff
00ff: 00 00 00 00 0f f0 01 64 ff ff 00 00 00 00 00 00    .......d........

Cc: Matteo Lisi <matteo.lisi@engicam.com>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Reviewed-by: Stefano Babic <sbabic@denx.de>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>

arch/arm/cpu/armv7/mx6/Kconfig

@@ -247,6 +247,7 @@ config TARGET_MX6UL_ISIOT
 	select OF_CONTROL
 	select DM
 	select DM_GPIO
+	select DM_I2C
 	select DM_MMC
 	select DM_THERMAL
 	select SUPPORT_SPL

configs/imx6ul_isiot_mmc_defconfig

@@ -21,6 +21,7 @@ CONFIG_SYS_PROMPT="isiotmx6ul> "
 # CONFIG_CMD_IMLS is not set
 CONFIG_CMD_MEMTEST=y
 CONFIG_CMD_MMC=y
+CONFIG_CMD_I2C=y
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_EXT2=y
@@ -29,6 +30,7 @@ CONFIG_CMD_EXT4_WRITE=y
 CONFIG_CMD_FAT=y
 CONFIG_CMD_FS_GENERIC=y
 # CONFIG_BLK is not set
+CONFIG_SYS_I2C_MXC=y
 # CONFIG_DM_MMC_OPS is not set
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_IMX6=y