[C61][DTO][EDP] Fix edp backlight's signals order and timings
The current configuration of the backlight can create problem with some panels; the new correct sequence is:
- VCC_BKL_EN (pca6416_20 9) - wait 40 ms
- PWM start - wait 10 ms
- iMX8_LVDS_BKL_ON (gpio4 4)