Input: bma150 - make some defines public and fix some comments

Make the constants referring to range and bandwidth public so they can
be used when initializing the platform data fields in the platform code.

Fix also some comments regarding the unit of measurement to use for the
range and bandwidth fields, the values are not actually expected to be
in G or HZ, the code in bma150.c just uses the BMA150_RANGE_xxx and
BMA150_BW_xxx constants like they are with no translation from actual
values in G or HZ.

Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Antonio Ospite <ao2@amarulasolutions.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>