qcacmn: Refine struct wmi_unified_pmk_cache (phase 3)

The original definition of struct wmi_unified_pmk_cache had several
anomalies:
1) It contains an unnecessary tlv_header field. Only the fw-api
   structs should contain TLV headers.
2) It contains a mis-named session_id field. Common structures should
   use converged terminology, in this case vdev_id

Change If4be27111c604c16ea437aa654210cdff28220a7 ("qcacmn: Refine
struct wmi_unified_pmk_cache (phase 1)") completely addressed the
first issue, and as the first phase of fixing the second issue it
replaced the session_id field with an anonymous union which contains
both the existing session_id field and a new vdev_id field. Being part
of a union these field will overlay each other.

qca-wifi-host_cmn change Ie8cc453751b95c332e3df32794506a4bd3c324ad
("qcacmn: Refine struct wmi_unified_pmk_cache (phase 2)") and
qcacld-3.0 change Ief4bcb819cb3c842adb74904f2cb2483476eaeb9
("qcacld-3.0: Use the refined struct wmi_unified_pmk_cache") replaced
all references to session_id with references to vdev_id.

For phase 3 remove the anonymous union introduced in phase 1, leaving
just the vdev_id field.

Change-Id: Ic5a274b9e2e8e603eef801a9d6422f55829f9735
CRs-Fixed: 2363432

wmi/inc/wmi_unified_sta_param.h

@@ -302,10 +302,7 @@ struct sar_limit_event {
  * @action_flag: add/delete the entry
  */
 struct wmi_unified_pmk_cache {
-	union {
 	uint8_t             vdev_id;
-	uint8_t             session_id;
-	};
 	uint32_t            pmk_len;
 	uint8_t             pmk[WMI_UNIFIED_MAX_PMK_LEN];
 	uint32_t            pmkid_len;