qapi script: clean up in scripts

This patch improve docs and uses c_type(argentry, is_param=True)
in script.

Signed-off-by: Wenchao Xia <wenchaoqemu@gmail.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index 3a1cd61..601e307 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -26,9 +26,8 @@
                 api_name += "bool has_%s,\n" % c_var(argname)
                 api_name += "".ljust(l)
 
-            if argentry == "str":
-                api_name += "const "
-            api_name += "%s %s,\n" % (c_type(argentry), c_var(argname))
+            api_name += "%s %s,\n" % (c_type(argentry, is_param=True),
+                                      c_var(argname))
             api_name += "".ljust(l)
 
     api_name += "Error **errp)"