UPSTREAM: backlight: pwm_bl: Remove useless call to pwm_set_period()

UPSTREAM: backlight: pwm_bl: Remove useless call to pwm_set_period()

The PWM period will be set when calling pwm_config. Remove this useless
call to pwm_set_period(), which might mess up the internal PWM state.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
(cherry picked from commit 7f044b09b68d36811518c55f736a20648e8ed6e2)

Change-Id: I6eecc6cd8e9dbe5929bdc016433772a721711928
Signed-off-by: David Wu <david.wu@rock-chips.com>