Addw2 support (#67)

* Add addw2 board

* Set charge params and update gpio.h

* Set VGA fan to 100% when entering scratch rom

* Implement keyboard LEDs

* Turn off keyboard LEDs in gpio defaults

* Default airplane mode LED to off

* Enable GPU power and fan control

* Add NVIDIA GPU power and temp to power.csv

* Add NVIDIA GPU fan value to power.sh

* Move GPU init back to coreboot

* Do not turn on GPU fan if GPU is off

* Show POST codes

* Add timestamps to console_external

* Accept port 81 cycles

* Move setting RSTS into ec_init

* Move post code debugging to system76/common

* Move some GPIO init from system76/common to boards

* Make some power signals optional

* Remove POST code support - it only works on IT5570

src/board/system76/common/pwm.c

@@ -10,6 +10,10 @@ void pwm_init(void) {
     // Set prescalar clock frequency to EC clock
     PCFSR = 0b01;
 
+    // Use C0CPRS and CTR0 for all channels
+    PCSSGL = 0;
+    PCSSGH = 0;
+
     // Set clock prescaler to 0 + 1
     C0CPRS = 0;