pwm: Add snapshot of QTI PWM LPG driver

The QTI PWM LPG driver supports the configuration of PWM/LPG channels on
QTI PMICs.

This is a snapshot of the driver taken from msm-4.19 as of commit
cf2cbb63fb60 ("Merge "input: touchscreen: synaptics_tcm: enable touch
driver"") with the following modifications:
  - Remove config_extend callback and pwm_get_period_extend()
  - Remove struct output_pattern and all its references
  - Remove enable, disable and config pwm_ops callbacks and instead use
    only apply()
  - Remove output_type callbacks
  - Remove support for dbg_show callback

Change-Id: I28571a8c6d5b0d5ac0cad113e77f3b5de8bf97c4
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>