wifi: mac80211: refactor BW limitation check for CSA parsing

Refactor the BW limitation check to a more general format when
parsing CSA. Also, the original BW check did not account for BW
less than 160 MHz.

Signed-off-by: Michael-CY Lee <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/spectmgmt.c

···
 		/* capture the AP chandef before (potential) downgrading */
 		csa_ie->chanreq.ap = new_chandef;
 
-		if (conn->bw_limit < IEEE80211_CONN_BW_LIMIT_320 &&
-		    new_chandef.width == NL80211_CHAN_WIDTH_320)
-			ieee80211_chandef_downgrade(&new_chandef, NULL);
-
-		if (conn->bw_limit < IEEE80211_CONN_BW_LIMIT_160 &&
-		    (new_chandef.width == NL80211_CHAN_WIDTH_80P80 ||
-		     new_chandef.width == NL80211_CHAN_WIDTH_160))
+		while (conn->bw_limit <
+			       ieee80211_min_bw_limit_from_chandef(&new_chandef))
 			ieee80211_chandef_downgrade(&new_chandef, NULL);
 
 		if (!cfg80211_chandef_compatible(&new_chandef,