qcacld-3.0: Fix for IBSS lock-up issue

During IBSS session tear down, we are hitting a lockup. The issue is
seen as the pdev->peer_ref_mutex is being taken up twice in
ol_txrx_remove_peers_for_vdev and ol_txrx_peer_unref_delete. The later
function gets invoked by the former and hence we are stuck while trying
to acquire the spinlock, the second time.

Fix issue by releasing peer_ref_mutex lock before invoking
callback (wma_remove_peer) in ol_txrx_remove_peers_for_vdev function.

The dmesg signature of the lock-up is as follows

1100.230392:   <2> [<ffffffc0002035a4>] el1_irq+0x64/0xd4
1100.235432:   <2> [<ffffffbffc17e890>]
ol_txrx_peer_unref_delete+0xc4/0x33c [wlan]
1100.242461:   <2> [<ffffffbffc17ecc8>] ol_txrx_peer_detach+0x1c0/0x1e0
[wlan]
1100.249020:   <2> [<ffffffbffc160914>] wma_remove_peer+0x7c/0x18c
[wlan]
1100.255141:   <2> [<ffffffbffc17dee4>]
ol_txrx_remove_peers_for_vdev+0x170/0x1b0 [wlan]
1100.262606:   <2> [<ffffffbffc16311c>]
wma_vdev_stop_resp_handler+0x204/0x460 [wlan]
1100.269816:   <2> [<ffffffbffc1886a8>] __wmi_control_rx+0x280/0x2c0
[wlan]
1100.276204:   <2> [<ffffffbffc188a34>] wmi_process_fw_event+0x8/0x14
[wlan]
1100.282595:   <2> [<ffffffbffc157054>] wma_mc_process_msg+0x80c/0x27fc
[wlan]
1100.289176:   <2> [<ffffffbffc13f238>] $x+0x190/0x3f4 [wlan]
1100.294115:   <2> [<ffffffc00023d7e8>] kthread+0xac/0xb8

CRs-Fixed: 1006847
Change-Id: Icedeb172bbd6736ab39343391ff0643ddd688444

core/dp/txrx/ol_txrx.c

@@ -1817,14 +1817,14 @@ ol_txrx_remove_peers_for_vdev(ol_txrx_vdev_handle vdev,
 			temp = peer;
 	}
 
+	qdf_spin_unlock_bh(&vdev->pdev->peer_ref_mutex);
+
 	if (remove_last_peer) {
 		/* remove IBSS bss peer last */
 		peer = TAILQ_FIRST(&vdev->peer_list);
 		callback(callback_context, (uint8_t *) &vdev->mac_addr,
 			 vdev->vdev_id, peer, false);
 	}
-
-	qdf_spin_unlock_bh(&vdev->pdev->peer_ref_mutex);
 }
 
 /**