ath11k-firmware: Move to new upstream repository for board-2.bin

ath11k-firmware: Move to new upstream repository for board-2.bin

It was announced [1] that the original staging repositories are no longer
used for staging of new firmware binaries. And that the old repository will
be removed [2] in June 2024.

The ath11k-firmware package must therefore point to the new repository
before the old one is no longer accessible.

[1] https://lore.kernel.org/r/bac97f31-4a70-4c4c-8179-4ede0b32f869@quicinc.com
[2] https://github.com/kvalo/ath11k-firmware/commit/8d2cc160f390badd62970a66483214773c3fbea1

Signed-off-by: Sven Eckelmann <sven@narfation.org>