wifi: b43: Replace outdated firmware URL

wifi: b43: Replace outdated firmware URL

https://wireless.wiki.kernel.org site now redirects to
https://wireless.docs.kernel.org/en/latest/ making the reference
information for the b43 firmware inaccessible. Update the URL to the
current location.

Link: https://bugs.debian.org/1095062
Signed-off-by: Salvatore Bonaccorso <carnil@debian.org>
Acked-by: Michael Büsch <m@bues.ch>
Link: https://patch.msgid.link/20250205110614.216958-1-carnil@debian.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>