Remove generated C files

[crawfxrd]

These files are generated while running proprietary firmware, but once they are added to coreboot they are no longer needed. They also quickly become stale as the files are always changed in coreboot.

find models/ -name gpio.h -exec rm {} \;
find models/ -name hda_verb.c -exec rm {} \;

Since I'm touching these files, also update the scripts that generate them to match what I actually add to coreboot.

• Generate gpio.c instead of gpio.h
• Add HDA reset to hda_verb.c