platform: qpnp-vibrator: Add support for qpnp-vibrator

Initial snapshot of leds-qpnp-vibrator driver is taken from
msm-3.18 kernel version @ commit f8b6819d0432d6 ("msm: ipa:
Fix to handle NULL pointer dereference")

The existing driver supports timed_output which is now
obsolete, modify it to support the control interface via
the LED class framework.

The usage is as below -
	For example, to enable vibrator for 10 sec
	$ echo 10000 > /sys/class/leds/vibrator/duration
	$ echo 1 > /sys/class/leds/vibrator/activate

Change-Id: Id9f165256472f5137260129c9ff39c0cd19943ed
Signed-off-by: Anindya Sundar Gayen <anindya@codeaurora.org>
Signed-off-by: Sundara Vinayagam <sundvi@codeaurora.org>