Fix goling failure in conversion public function doc

The exported or public functions without a comment results into golint failure
in various generated files. The changes in this patch takes care of about 36
related lint failures.
Given below is an example lint error,
zz_generated.conversion.go:91:1: exported function
Convert_v1alpha1_Binding_To_servicecatalog_Binding should have comment or be
unexported

cmd/libs/go2idl/conversion-gen/generators/conversion.go

@@ -580,6 +580,7 @@ func (g *genConversion) generateConversion(inType, outType *types.Type, sw *gene
 		}
 	} else {
 		// Emit a public conversion function.
+		sw.Do("// "+nameTmpl+" is an autogenerated conversion function.\n", args)
 		sw.Do("func "+nameTmpl+"(in *$.inType|raw$, out *$.outType|raw$, s $.Scope|raw$) error {\n", args)
 		sw.Do("return auto"+nameTmpl+"(in, out, s)\n", args)
 		sw.Do("}\n\n", nil)