MAINTAINERS: wifi: update ath.git location

ath.git tree has moved to a new location. The old location will be an alias to
the new location and will work at least until end of 2024, but best to update
git trees already now.

Signed-off-by: Kalle Valo <kvalo@kernel.org>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://patch.msgid.link/20240626102632.1554485-1-kvalo@kernel.org