iio:magnetometer:bmc150_magn: sort entry alphabetically

Sort the entry for bmc105_magn in Kconfig and Makefile to its correct
position. Also add the minor module information for completeness.

Fixes: c91746a2 ("iio: magn: Add support for BMC150 magnetometer")

Signed-off-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>