Bluetooth: Fix ATT MTU size to 23

We only support a 23 octet MTU, so auto-respond to all
MTU change requests with the 23 octet response.

Change-Id: Ic69d5f068759d983f8cd98b329acbb9d3a481c49
CRs-fixed: 336025
Signed-off-by: Brian Gix <bgix@codeaurora.org>
diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 312de3f..09c1b7f 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -648,6 +648,8 @@
 #define L2CAP_AMP_STATE_RESEGMENT		12
 
 #define L2CAP_ATT_ERROR				0x01
+#define L2CAP_ATT_MTU_REQ			0x02
+#define L2CAP_ATT_MTU_RSP			0x03
 #define L2CAP_ATT_RESPONSE_BIT			0x01
 #define L2CAP_ATT_INDICATE			0x1D
 #define L2CAP_ATT_NOT_SUPPORTED			0x06