remove duplicate lemma Suc_numeral

--- a/src/HOL/Nat_Numeral.thy	Thu Mar 29 14:09:10 2012 +0200
+++ b/src/HOL/Nat_Numeral.thy	Thu Mar 29 14:29:36 2012 +0200
@@ -40,10 +40,6 @@
   "Suc (numeral v + n) = numeral (v + Num.One) + n"
   by simp
 
-lemma Suc_numeral [simp]:
-  "Suc (numeral v) = numeral (v + Num.One)"
-  by simp
-
 
 subsubsection{*Subtraction *}