Fix coverity warnings in VOM and VAPI

Change-Id: I0db55e079f9b1835668c8efe69e6e6f7f8437b00
Signed-off-by: Neale Ranns <neale.ranns@cisco.com>
diff --git a/src/vpp-api/vapi/vapi_c_gen.py b/src/vpp-api/vapi/vapi_c_gen.py
index d7a7272..4b7da6a 100755
--- a/src/vpp-api/vapi/vapi_c_gen.py
+++ b/src/vpp-api/vapi/vapi_c_gen.py
@@ -504,11 +504,11 @@
             '    offsetof(%s, context),' % self.header.get_c_name()
             if has_context else '    0,',
             ('    offsetof(%s, payload),' % self.get_c_name())
-            if self.has_payload() else '    ~0,',
+            if self.has_payload() else '    INVALID_MSG_ID,',
             '    sizeof(%s),' % self.get_c_name(),
             '    (generic_swap_fn_t)%s,' % self.get_swap_to_be_func_name(),
             '    (generic_swap_fn_t)%s,' % self.get_swap_to_host_func_name(),
-            '    ~0,',
+            '    INVALID_MSG_ID,',
             '  };',
             '',
             '  %s = vapi_register_msg(&%s);' %