pico-serprog

Riku introduced three new patches:

* Add support for multiple chip selects. This allows you to
  control multiple chips from the same clip, on systems with
  dual flash setups, at least theoretically.
* Enable pull-up on unused chip selects - pull them high so
  that chips you connect that to are deactivated while flashing
  the target chip. This could be used on thinkpad W541 for
  instance, where miso/mosi have 0ohm between them via the two
  flash ICs. You could pull the other chip select high.
* Documentation for the above, in the pico-serprog readme.

This goes in tandem with a patch from Riku, present in the
recently integrated flashprog project, namely:

commit ddb6d926783d4f9cbee04c7392718ed8f89daa0e
Author: Riku Viitanen <riku.viitanen@protonmail.com>
Date:   Mon Jan 15 19:15:49 2024 +0200

    serprog: Add support for multiple SPI chip selects

This functionality will therefore be present in the next
release of Libreboot.

Signed-off-by: Leah Rowe <leah@libreboot.org>