mwifiex: correct bss_mode check while appending vht operation IE

priv->bss_mode uses NL80211_IFTYPE_* definitions.
HostCmd_BSS_MODE_IBSS is used in ad-hoc start/join command between
driver and firmware.

Coincidentally both HostCmd_BSS_MODE_IBSS and NL80211_IFTYPE_STATION
are defined as 2. That explains why nobody complained.
Signed-off-by: NBing Zhao <bzhao@marvell.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/11ac.c

@@ -200,7 +200,7 @@ int mwifiex_cmd_append_11ac_tlv(struct mwifiex_private *priv,
 
 	/* VHT Operation IE */
 	if (bss_desc->bcn_vht_oper) {
-		if (priv->bss_mode == HostCmd_BSS_MODE_IBSS) {
+		if (priv->bss_mode == NL80211_IFTYPE_STATION) {
 			vht_op = (struct mwifiex_ie_types_vht_oper *)*buffer;
 			memset(vht_op, 0, sizeof(*vht_op));
 			vht_op->header.type =