rtlwifi: Add encryption argument in rtl_is_special_data for checking DHCP packet.

rtl8192cu can't connect to AP after physical reconnect.
according to dmesg, that problem's cause was DHCP timeout.

rtl_is_special_data function checks packet type for adjusting rate.
when that function is called from _rtl_rc_get_highest_rix, it can not
calculate offset correctly. so i add argument is_encn in rtl_is_special_data.
is_enc variable mean that iv header is added in skb parameter.

i test only rtl8192cu chipset. because i doesn't have other rtlwifi chipsets.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
diff --git a/drivers/net/wireless/rtlwifi/rc.c b/drivers/net/wireless/rtlwifi/rc.c
index 7863bd2..74c14ce 100644
--- a/drivers/net/wireless/rtlwifi/rc.c
+++ b/drivers/net/wireless/rtlwifi/rc.c
@@ -56,7 +56,8 @@
 		wireless_mode = sta_entry->wireless_mode;
 	}
 
-	if (rtl_is_special_data(rtlpriv->mac80211.hw, skb, true) || not_data) {
+	if (rtl_is_special_data(rtlpriv->mac80211.hw, skb, true, false) ||
+	    not_data) {
 		return 0;
 	} else {
 		if (rtlhal->current_bandtype == BAND_ON_2_4G) {
@@ -201,7 +202,7 @@
 	if (!priv_sta || !ieee80211_is_data(fc))
 		return;
 
-	if (rtl_is_special_data(mac->hw, skb, true))
+	if (rtl_is_special_data(mac->hw, skb, true, true))
 		return;
 
 	if (is_multicast_ether_addr(ieee80211_get_DA(hdr)) ||