wilc1000: add vmm_table entry validity check before accessing Txq

Add Tx VMM buffer validity check before accessing the buffer entity to
avoid any access to invalid value. It's handled by moving 'vmm_table' entry
check before calling wilc_wlan_txq_remove_from_head().

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>

Author: ajaykathat

drivers/net/wireless/microchip/wilc1000/wlan.c

@@ -1152,14 +1152,14 @@ int wilc_wlan_handle_txq(struct wilc *wilc, u32 *txq_count)
 		u32 header, buffer_offset;
 		u8 mgmt_ptk = 0;
 
-		tqe = wilc_wlan_txq_remove_from_head(wilc, vmm_entries_ac[i]);
-		ac_pkt_num_to_chip[vmm_entries_ac[i]]++;
-		if (!tqe)
+		if (vmm_table[i] == 0 || vmm_entries_ac[i] >= NQUEUES)
 			break;
 
-		if (vmm_table[i] == 0)
+		tqe = wilc_wlan_txq_remove_from_head(wilc, vmm_entries_ac[i]);
+		if (!tqe)
 			break;
 
+		ac_pkt_num_to_chip[vmm_entries_ac[i]]++;
 		vif = tqe->vif;
 		le32_to_cpus(&vmm_table[i]);
 		vmm_sz = FIELD_GET(WILC_VMM_BUFFER_SIZE, vmm_table[i]);