qcacld-3.0: Add NULL pointer validation on pmkid received

In wlan_hdd_extauth_copy_pmkid(), pmkid received from userspace
could be NULL. Currently there is no validation for the PMKID.

Add check to validate the received PMKID before copy.

Change-Id: I756458562bf20226a202a5ecdbbe9e79884169c7
CRs-Fixed: 2508935

core/hdd/src/wlan_hdd_cfg80211.c

@@ -21708,6 +21708,7 @@ static void
 wlan_hdd_extauth_copy_pmkid(struct cfg80211_external_auth_params *params,
 			    uint8_t *pmkid)
 {
+	if (params->pmkid)
 		qdf_mem_copy(pmkid, params->pmkid, PMKID_LEN);
 }