tests/avocado/machine_aspeed.py: Update buildroot images to 2023.11

tests/avocado/machine_aspeed.py: Update buildroot images to 2023.11

Compared to mainline buildroot, these images have some customization :

- Linux version is bumped to 6.6.3 and built with a custom config
- U-Boot is switched to the one provided by OpenBMC for more support
- defconfigs extra tools for dev

See branch [1] for more details.

There are a few changes since last update, commit ed1f5ff84209. Images
all have a password now and I2C devices have been updated in the Linux
ast2600-evb device tree [2]. Do the necessary adjustements.

[1] https://github.com/legoater/buildroot/commits/aspeed-2023.11
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9deb10cf160e

Signed-off-by: Cédric Le Goater <clg@kaod.org>