hlte: enable userspace vibration strength control (2/2)

This requires kernel-side implementation:
"tspdrv: add userspace vibration strength control (1/2)"

Original implementation taken from:
https://github.com/CyanogenMod/android_device_lge_hammerhead/commit/4abd8c761c1e81a997935aa5394218eacf908563

Change-Id: I60c61d01e97739335f66975fb303b883eb47b70d
Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>