apps/bttester: Increase number of supported L2CAP CoC channels

Increase BLE_L2CAP_COC_MAX_NUM value to 3. This was affecting
L2CAP/ECFC/BV-27-C qualification test case.


diff --git a/apps/bttester/syscfg.yml b/apps/bttester/syscfg.yml
index d1e37ab..68a60f6 100644
--- a/apps/bttester/syscfg.yml
+++ b/apps/bttester/syscfg.yml
@@ -97,7 +97,7 @@
     RTT_NUM_BUFFERS_UP: 0
     RTT_NUM_BUFFERS_DOWN: 0
 
-    BLE_L2CAP_COC_MAX_NUM: 2
+    BLE_L2CAP_COC_MAX_NUM: 3
     BLE_L2CAP_SIG_MAX_PROCS: 2
     BLE_L2CAP_ENHANCED_COC: 1
     BLE_EATT_CHAN_NUM: 5