input: sensors: add support to schedule data poll on idle CPU

In order to boost sensor data polling/processing performance
for accel,gyro and mag sensors on various platforms, use kthread
instead of workqueue and set_wake_up_idle() for high frequency
streaming usecase. Set max fifo count to zero for accel to disable
default FIFO use.

Change-Id: I63905856b28098dd02375854f451c1687c560156
Signed-off-by: Kiran Raparthy <krapar@codeaurora.org>