staging: rtl8723bs: put constant on the right side of a test in os_dep/ioctl_cfg80211.c

fix following post-commit hook checkpatch issue:

CHECK: Comparison to NULL could be written "psta"
72: FILE: drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c:854:
+			if (psta != NULL) {

Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
Link: https://lore.kernel.org/r/5ac547f3a4bd228f372da7057bbfb3cac1535857.1618064274.git.fabioaiuto83@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c

@@ -851,7 +851,7 @@ static int rtw_cfg80211_set_encryption(struct net_device *dev, struct ieee_param
 		if (check_fwstate(pmlmepriv, WIFI_STATION_STATE | WIFI_MP_STATE) == true) /* sta mode */
 		{
 			psta = rtw_get_stainfo(pstapriv, get_bssid(pmlmepriv));
-			if (psta != NULL) {
+			if (psta) {
 				/* Jeff: don't disable ieee8021x_blocked while clearing key */
 				if (strcmp(param->u.crypt.alg, "none") != 0)
 					psta->ieee8021x_blocked = false;