wifi: ath9k: ath9k_set_moredata(): fix sparse warnings

Sparse warns:

drivers/net/wireless/ath/ath9k/xmit.c:1677:20: warning: incorrect type in initializer (different base types)
drivers/net/wireless/ath/ath9k/xmit.c:1677:20:    expected unsigned short [usertype] mask
drivers/net/wireless/ath/ath9k/xmit.c:1677:20:    got restricted __le16 [usertype]
drivers/net/wireless/ath/ath9k/xmit.c:1681:17: warning: restricted __le16 degrades to integer
drivers/net/wireless/ath/ath9k/xmit.c:1682:42: warning: restricted __le16 degrades to integer
drivers/net/wireless/ath/ath9k/xmit.c:1682:36: warning: incorrect type in assignment (different base types)
drivers/net/wireless/ath/ath9k/xmit.c:1682:36:    expected restricted __le16 [usertype] frame_control
drivers/net/wireless/ath/ath9k/xmit.c:1682:36:    got int

Fix ath9k_set_moredata() to use __le16 with masks and use if statement instead
of multiply operator.

Compile tested only.

Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://msgid.link/20240320170656.3534265-2-kvalo@kernel.org

drivers/net/wireless/ath/ath9k/xmit.c

@@ -1674,8 +1674,14 @@ static void
 ath9k_set_moredata(struct ath_softc *sc, struct ath_buf *bf, bool val)
 {
 	struct ieee80211_hdr *hdr;
-	u16 mask = cpu_to_le16(IEEE80211_FCTL_MOREDATA);
-	u16 mask_val = mask * val;
+	__le16 mask, mask_val;
+
+	mask = cpu_to_le16(IEEE80211_FCTL_MOREDATA);
+
+	if (val)
+		mask_val = mask;
+	else
+		mask_val = 0;
 
 	hdr = (struct ieee80211_hdr *) bf->bf_mpdu->data;
 	if ((hdr->frame_control & mask) != mask_val) {