iio: accel: kxsd9: Add I2C transport

This adds I2C regmap transport for the KXSD9 driver.
Tested on the KXSD9 sensor on the APQ8060 Dragonboard.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
index 2fe41d7..b5c2a0b 100644
--- a/drivers/iio/accel/Makefile
+++ b/drivers/iio/accel/Makefile
@@ -14,6 +14,7 @@
 obj-$(CONFIG_KXCJK1013) += kxcjk-1013.o
 obj-$(CONFIG_KXSD9)	+= kxsd9.o
 obj-$(CONFIG_KXSD9_SPI)	+= kxsd9-spi.o
+obj-$(CONFIG_KXSD9_I2C)	+= kxsd9-i2c.o
 
 obj-$(CONFIG_MMA7455)		+= mma7455_core.o
 obj-$(CONFIG_MMA7455_I2C)	+= mma7455_i2c.o