[realtek-ambz2] Define PIN_SERIAL0_RX/TX for wbr3

[nmschulte]

This is necessary; WBR3 is not in the feature/i2c-spi branch, and this fixes about feature/realtek-update without the concerns of feature/i2c-spi -- perhaps I misunderstand the relevant comment, however.

#44 (comment)

baltpeter@a92983a

[kuba2k2]

Hi
This file is auto-generated, so it shouldn't be changed. It will get overwritten after every update processed with boardgen.
The ESPHome code is not ready for the fixes introduced in the feature/realtek-update branch, which makes it incorrectly understand the available serial ports.
However, I can merge this PR to that branch as a temporary workaround.

[nmschulte]

In that case, I'd say merging is unnecessary -- it sounds like I should focus my efforts on ESPHome and working against the changes you mention. Thanks for helping my understanding here.