When you reopen the lid on a laptop with PCH, the panel suddenly goes
blank sometimes. It seems because BLC_PWM_CPU_CTL register is cleared
to zero when BLC_PWM_CPU_CTL2 and BLC_PWM_PCH_CTL1 registers are
enabled.
This patch fixes the problem by moving the call of the function setting
BLC_PWM_CPU_CTL after enabling other two registers.