qcacld-3.0: Fix mac_handle test in hdd_set_dwell_time()

Recently change "qcacld-3.0: Use mac_handle_t in wlan_hdd_ioctl"
updated the nomenclature used in HDD. During the implementation of
this change a NULL check of mac_handle in hdd_set_dwell_time() had a
"!" removed, incorrectly changing the logic. Restore the correct logic
for NULL-checking mac_handle.

Change-Id: I2bb8393d5adb3156795b3b722d839812419e4995
CRs-Fixed: 2299812

core/hdd/src/wlan_hdd_ioctl.c

@@ -2288,7 +2288,7 @@ static int hdd_set_dwell_time(struct hdd_adapter *adapter, uint8_t *command)
 	int retval = 0;
 
 	pCfg = (WLAN_HDD_GET_CTX(adapter))->config;
-	if (!pCfg || mac_handle) {
+	if (!pCfg || !mac_handle) {
 		hdd_err("argument passed for SETDWELLTIME is incorrect");
 		return -EINVAL;
 	}