qpnp: pwm: Add support for additional pwm sizes

The existing pwm driver only supports 6 and 9bit pwm modes. It is
a limitation to the pwm use-cases and some of the LPG channels
do not even support these PWM bit modes. Thus, add the support
for the rest of the available bit modes.

Change-Id: I09ad379358c230c2e9fbe2715bdce9cc145dd8af
Signed-off-by: Jay Chokshi <jchokshi@codeaurora.org>