930 bug fixes for garter carriage alignment and lace carriage start selection

[clholgat]

Update offsets for G carriage on the 930

Make sure to calculate the first HALF_SOLENOID pixels when the lace carriage is selected.

Addresses:

• https://github.com/AllYarnsAreBeautiful/ayab-firmware/issues/180
• https://github.com/AllYarnsAreBeautiful/ayab-firmware/issues/178