drivers: platform: msm: qpnp-vibrator: Add sysfs interface for intensity

To control the Haptic intensity using sysfs interface.

Change-Id: If0ccd421b6dbe0d0602f427af12f08dab2235036
Signed-off-by: SpaceKiller <alexisalbo.1@gmail.com>

msm: Improve qpnp-vibrator scheduling

 * Skip the workqueue and use spinlocks to improve interactivity
 * This vastly improves "recent apps" in Android

Change-Id: I77da17b4f1ce2f213772c41ddbac21250432279e