pwm: qti-lpg: Correct PWM_SIZE setting for PWM module

PWM module with subtype value 0xb has different register mapping on
PWM_SIZE with LPG module, so read the subtype and apply the PWM_SIZE
setting according to different subtype values.

Change-Id: I5222de22345784399c113656414811cc7d6ec47b
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>