drivers: pwm: re-design pwm API interfaces

Re-design the pwm API interfaces. A RFC was sent and discussed
recently on the re-design of PWM APIs.

APIs like pwm_pin_set_values, pwm_pin_set_period, pwm_pin
_set_duty_cycle will be deprecated and replaced by the new
APIs pwm_pin_set_cycles and pwm_pin_set_usec.

A new API pwm_get_cycles_per_sec will be added to get the
clock rate for pwm pins.

The API pwm_pin_set_phase will be deprecated(it always sets
the phase to zero).

The API pwm_pin_configure will be deprecated since it is not
doing anything for most of the platforms or it can be moved
to device init function for the other platforms.

All the pwm_all_xxx APIs will be deprecated. If necessary,
user or an app can set the pins individually.

Jira: ZEP-745

Change-Id: Ie7095df2a67cff08873b59794812ac64ee00c1c2
Signed-off-by: Baohong Liu <baohong.liu@intel.com>