tests/multi_bluetooth: Use multitest.output_metric in BLE perf tests.

Signed-off-by: Damien George <damien@micropython.org>

tests/multi_bluetooth/perf_gatt_char_write.py

@@ -128,7 +128,7 @@ def instance1():
             ticks_end = time.ticks_ms()
             ticks_total = time.ticks_diff(ticks_end, ticks_start)
 
-            print(
+            multitest.output_metric(
                 "Did {} writes in {} ms. {} ms/write, {} bytes/sec".format(
                     _NUM_NOTIFICATIONS,
                     ticks_total,

tests/multi_bluetooth/perf_gatt_notify.py

@@ -90,7 +90,7 @@ def instance0():
 
         ticks_end = time.ticks_ms()
         ticks_total = time.ticks_diff(ticks_end, ticks_start)
-        print(
+        multitest.output_metric(
             "Acknowledged {} notifications in {} ms. {} ms/notification.".format(
                 _NUM_NOTIFICATIONS, ticks_total, ticks_total // _NUM_NOTIFICATIONS
             )

tests/multi_bluetooth/perf_gatt_notify.py.exp

@@ -0,0 +1,5 @@
+--- instance0 ---
+gap_advertise
+gap_disconnect: True
+--- instance1 ---
+gap_connect

tests/multi_bluetooth/perf_l2cap.py

@@ -134,7 +134,7 @@ def instance1():
         ble.l2cap_disconnect(conn_handle, cid)
         wait_for_event(_IRQ_L2CAP_DISCONNECT, TIMEOUT_MS)
 
-        print(
+        multitest.output_metric(
             "Received {}/{} bytes in {} ms. {} B/s".format(
                 recv_bytes, recv_correct, total_ticks, recv_bytes * 1000 // total_ticks
             )

tests/multi_bluetooth/perf_l2cap.py.exp

@@ -0,0 +1,4 @@
+--- instance0 ---
+
+--- instance1 ---
+