input: sensors: add auto report support for akm09911

The raw magnetic data is parsed and calculated into magnetic field
intensity based values after auto-report mode is enabled. The usespace
HAL can either send them directly to Android framework or calibrate
them into more accurate values.

Change-Id: I98cd6051f7b9972afac0503c23a4f43c3752002e
Signed-off-by: Oliver Wang <mengmeng@codeaurora.org>