Move serial init to earlier in boot process

[gneverov]

In my case:

1. wait for safe mode flashes the led
2. the led on a pico-w needs the cyg43 driver
3. the cyg43 driver prints to console that it loaded
4. print crashes since uart is not initialized

This only happens if the console uart is enabled, which it is not on production builds of this board.

[dhalbert]

Makes sense, thanks!

[tannewt]

I think this might be the console uart used for ESP32 and C3 in production builds. (Starting early might be ok still though.)