Make pi uart default to on and console login disabled

[bmidgley]

The most common use for the pi's uart would be a gps right? gps hats are commonly wired to the uart. But I had to disable the login and enable the uart hardware. It'll be easier if that's a default.

[edfardos]

Mostly commonly gps, including on DigiPi hat, but I agree, there's no need for a getty on the hardware serial port.