video: atmel_hlcd: make LCD pwm clock prescaler configurable

make LCD pwm clock prescaler configurable

Signed-off-by: Bo Shen <voice.shen@atmel.com>
video: atmel: using mck as default clock for PWM

using mck as default clock for PWM to control the backlight

Signed-off-by: Bo Shen <voice.shen@atmel.com>
ARM: sama5: configure LCD pwm clock prescaler to DIV_32

configure LCD pwm clock prescaler to DIV_32

Signed-off-by: Bo Shen <voice.shen@atmel.com>