input: sensor: add power control in sensor enable sysfs for mpu3050

Add the sensor power management in the enable sysfs interface,
through which the HAL layer could enable/disable the sensor.

Change-Id: I68d77a5085e2d80deedb273f0ff1e0d5664ba71c
Signed-off-by: Xiaocheng Li <lix@codeaurora.org>