Major warnings cleanup

Mostly fixing unused parameter warnings.
A few other warnings also fixed like possible use of
unitialized variables (no real issue found, just compiler couldn't
follow the path), signed vs unsigned warning.

Also fixed some typos, indent issues, removal of dead code, etc.

Change-Id: I95eb887aefc4d559d7921f71a0af5f3bfb01ac01
Signed-off-by: Mike J. Chen <mjchen@google.com>
diff --git a/bta/ag/bta_ag_main.c b/bta/ag/bta_ag_main.c
index 9b28067..bae992b 100644
--- a/bta/ag/bta_ag_main.c
+++ b/bta/ag/bta_ag_main.c
@@ -28,6 +28,7 @@
 #include "bta_ag_co.h"
 #include "bta_ag_int.h"
 #include "bd.h"
+#include "utl.h"
 
 /*****************************************************************************
 ** Constants and types
@@ -586,6 +587,8 @@
 {
     UINT16  handle;
     tBTA_AG_SCB *p_scb;
+    UNUSED(status);
+    UNUSED(app_id);
 
     /* Check if we have opening scb for the peer device. */
     handle = bta_ag_idx_by_bdaddr (peer_addr);