wifi: mt76: mt7615: add missing chanctx ops

Here's another one I missed during the initial conversion,
fix that.

Cc: stable@vger.kernel.org
Reported-by: Rene Petersen <renepetersen@posteo.de>
Fixes: 0a44dfc0

 ("wifi: mac80211: simplify non-chanctx drivers")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218895
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240528142308.3f7db1821e68.I531135d7ad76331a50244d6d5288e14aa9668390@changeid