iio: bmg160: Separate i2c and core driver

This patch separates the core driver using regmap and the i2c driver
which creates the i2c regmap. Also in the Kconfig file BMG160 and
BMG160_I2C are separate now.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/gyro/Makefile b/drivers/iio/gyro/Makefile
index f46341b..6084010 100644
--- a/drivers/iio/gyro/Makefile
+++ b/drivers/iio/gyro/Makefile
@@ -8,7 +8,8 @@
 obj-$(CONFIG_ADIS16136) += adis16136.o
 obj-$(CONFIG_ADIS16260) += adis16260.o
 obj-$(CONFIG_ADXRS450) += adxrs450.o
-obj-$(CONFIG_BMG160) += bmg160.o
+obj-$(CONFIG_BMG160) += bmg160_core.o
+obj-$(CONFIG_BMG160_I2C) += bmg160_i2c.o
 
 obj-$(CONFIG_HID_SENSOR_GYRO_3D) += hid-sensor-gyro-3d.o