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

To control the Haptic intensity using sysfs interface.

Signed-off-by: SpaceKiller <alexisalbo.1@gmail.com>
Signed-off-by: Blechd0se <alex.christ@hotmail.de>
Fix vibrator sysfs

Change-Id: Ic33ab91b35039bb3ca9f42949dfffdb34b6276b1
Signed-off-by: Blechd0se <alex.christ@hotmail.de>
platform: msm: vibrator: handle out of range properly

If one changes the strength to something which is not in range
of the default values the previous implementation would either
swtich to maxiumum or minimum.
Thats not really needed, we can just stay on the previous one
and return early, furthermore we can simplify this.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>