mwifiex: CPU mips optimization with NO_PKT_PRIO_TID

If we go through the entire for loop in
mwifiex_wmm_get_highest_priolist_ptr() and don't find any packets,
set highest_queued_prio to NO_PKT_PRIO_TID (< LOW_PRIO_TID).
Signed-off-by: Marc Yang <yangyang@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/main.h

@@ -202,6 +202,7 @@ struct mwifiex_tid_tbl {
 #define WMM_HIGHEST_PRIORITY		7
 #define HIGH_PRIO_TID				7
 #define LOW_PRIO_TID				0
+#define NO_PKT_PRIO_TID				(-1)
 
 struct mwifiex_wmm_desc {
 	struct mwifiex_tid_tbl tid_tbl_ptr[MAX_NUM_TID];

drivers/net/wireless/mwifiex/wmm.c

@@ -946,6 +946,12 @@ mwifiex_wmm_get_highest_priolist_ptr(struct mwifiex_adapter *adapter,
 				} while (ptr != head);
 			}
 
+			/* No packet at any TID for this priv. Mark as such
+			 * to skip checking TIDs for this priv (until pkt is
+			 * added).
+			 */
+			atomic_set(hqp, NO_PKT_PRIO_TID);
+
 			/* Get next bss priority node */
 			bssprio_node = list_first_entry(&bssprio_node->list,
 						struct mwifiex_bss_prio_node,