iio: imu: add BNO055 serdev driver

This path adds a serdev driver for communicating to a BNO055 IMU
via serial bus, and enables the BNO055 core driver to work in this
scenario.

Signed-off-by: Andrea Merello <andrea.merello@iit.it>
Cc: Andrea Merello <andrea.merello@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Matt Ranostay <matt.ranostay@konsulko.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Vlad Dogaru <vlad.dogaru@intel.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-iio@vger.kernel.org

drivers/iio/imu/bno055/Kconfig

@@ -5,3 +5,8 @@
 
 config BOSH_BNO055_IIO
 	tristate
+
+config BOSH_BNO055_SERIAL
+	tristate "Bosh BNO055 attached via serial bus"
+	depends on SERIAL_DEV_BUS
+	select BOSH_BNO055_IIO

drivers/iio/imu/bno055/Makefile

@@ -4,3 +4,4 @@
 #
 
 obj-$(CONFIG_BOSH_BNO055_IIO) += bno055.o
+obj-$(CONFIG_BOSH_BNO055_SERIAL) += bno055_sl.o