wifi: mac80211: fix incorrect type for ret

The variable ret is declared as a u32 type, but it is assigned a value
of -EOPNOTSUPP. Since unsigned types cannot correctly represent negative
values, the type of ret should be changed to int.

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

net/mac80211/driver-ops.h

···
 			    struct ieee80211_sub_if_data *sdata,
 			    struct cfg80211_ftm_responder_stats *ftm_stats)
 {
-	u32 ret = -EOPNOTSUPP;
+	int ret = -EOPNOTSUPP;
 
 	might_sleep();
 	lockdep_assert_wiphy(local->hw.wiphy);