qpnp: pwm: remove the PWM Channel ID dependency

Existing driver uses the PWM channel ID to identify
PWM sizes are supported and to enable RAMP_CONTROL
register in LUT mode.

To support more than one PMIC chip in system,
this channel ID dependency breaks LPG functionality.
So add supported_sizes field for every LPG/PWM to
dynamically identify supported sizes of LPG/PWM channel.

Also to start the ramp in LPG mode, ramp_index is required
for every LPG to update the RAMP_CONTROL register without
depending on channel ID.

Change-Id: Ic4a73c7ea1b8d581d71687a7baaf411b67851f0e
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>