input: sensors: add sensor class support for BOSCH bma2x2

Sensor class interface is required for sensor HAL to discover
the sensor. This change adds sensor class support for BOSCH
bma2x2 accelerometer.

CRs-fixed: 653165
Change-Id: If9dbddff3b4a58f21945a5da7dc4dbcec9c2e178
Signed-off-by: Oliver Wang <mengmeng@codeaurora.org>
Signed-off-by: Bingzhe Cai <bingzhec@codeaurora.org>