HS 2.0: Do not check OSU_SSID against WLAN_TAG2 SSID in single-BSS case

The OSU_SSID parameter can be used in the single-BSS case without
WLAN_TAG2. This combination resulted in the "OSU_SSID and WLAN_TAG2 SSID
differ" error. Fix that by skipping this check if the WLAN_TAG2 has not
been used.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
diff --git a/ap.c b/ap.c
index 303069f..d871303 100644
--- a/ap.c
+++ b/ap.c
@@ -2585,7 +2585,8 @@
 		}
 
 		if (strlen(dut->ap_osu_ssid)) {
-			if (strcmp(dut->ap_tag_ssid[0],
+			if (dut->ap_tag_ssid[0][0] &&
+			    strcmp(dut->ap_tag_ssid[0],
 				   dut->ap_osu_ssid) != 0 &&
 			    strcmp(dut->ap_tag_ssid[0], osu_ssid) != 0) {
 				sigma_dut_print(dut, DUT_MSG_ERROR,
@@ -4318,7 +4319,8 @@
 		}
 
 		if (strlen(dut->ap_osu_ssid)) {
-			if (strcmp(dut->ap_tag_ssid[0], dut->ap_osu_ssid) &&
+			if (dut->ap_tag_ssid[0][0] &&
+			    strcmp(dut->ap_tag_ssid[0], dut->ap_osu_ssid) &&
 			    strcmp(dut->ap_tag_ssid[0], osu_ssid)) {
 				sigma_dut_print(dut, DUT_MSG_ERROR,
 						"OSU_SSID and "