leds: Add snapshot of QTI Tri-LED driver

The QTI Tri-LED driver enables the configuration of the output of LED
channels in the TRI_LED and HR_LED peripherals found in 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 the setting of struct pwm_output_pattern to NULL in
    __tri_led_config_pwm()
  - Remove LED_KEEP_TRIGGER from qpnp_tri_led_register()
  - Add a MODULE_SOFTDEP link to the QTI PWM LPG driver so that modprobe
    can enforce the functional dependency on it.

Change-Id: I7ceb2ff1a9ed1fec09651744ec2e7b2ba73f1bae
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>