qpnp: pwm: Force the pwm size selection

For certain use cases pwm size need to restricted
to avoid dynamic pwm size selection based on the
pwm period value. Currently pwm freqency and pwm
sizes are selected for a given pwm period. Restrict
pwm size to a specific value and select pwm frequency
closest to pwm period requested.

CRs-Fixed: 529920
Change-Id: I42d4d9621312adf25061b7a9b52056806f8d9b2b
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>