rtlwifi: rtl8821ae: phy: Simplify bool comparison

Fix the following coccicheck warning:

./drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c:3853:7-17:
WARNING: Comparison of 0/1 to bool variable.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1612840381-109714-1-git-send-email-jiapeng.chong@linux.alibaba.com

drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c

@@ -3848,7 +3848,7 @@ static void _rtl8821ae_iqk_tx(struct ieee80211_hw *hw, enum radio_path path)
 			else
 				rtl_write_dword(rtlpriv, 0xc8c, 0x00163e96);
 
-			if (vdf_enable == 1) {
+			if (vdf_enable) {
 				rtl_dbg(rtlpriv, COMP_IQK, DBG_LOUD, "VDF_enable\n");
 				for (k = 0; k <= 2; k++) {
 					switch (k) {