leds: leds-qpnp: Always configure PWM period in qpnp_rgb_set

Now that PWM framework requires the PWM period to be set prior to enable
the PWM channel, always configure PWM period and duty in qpnp_rgb_set()
function to make sure that pwm_enable() is successfully called.

CRs-Fixed: 2161149
Change-Id: Ib9eb818861a8219b39d94f97af1b7b9f8168b446
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>