Using the dedicated manifest constant is more descriptive.

2012-07-24  Jan Beulich <jbeulich@suse.com>

	* config/tc-i386-intel.c (i386_intel_simplify_register):
	Replace literal 4 by corresponding ESP_REG_NUM.

--- a/gas/config/tc-i386-intel.c
+++ b/gas/config/tc-i386-intel.c
@@ -285,7 +285,7 @@ i386_intel_simplify_register (expression
   else
     {
       /* esp is invalid as index */
-      intel_state.index = i386_regtab + REGNAM_EAX + 4;
+      intel_state.index = i386_regtab + REGNAM_EAX + ESP_REG_NUM;
     }
   return 2;
 }
@@ -440,7 +440,7 @@ static int i386_intel_simplify (expressi
 		break;
 	      default:
 		/* esp is invalid as index */
-		intel_state.index = i386_regtab + REGNAM_EAX + 4;
+		intel_state.index = i386_regtab + REGNAM_EAX + ESP_REG_NUM;
 		break;
 	      }