x86: Fix do_go_exec()

This was broken a long time ago by a49864593e083a5d0779fb9ca98e5a0f2053183d
which munged the NIOS and x86 do_go_exec()

Signed-off-by: Graeme Russ <graeme.russ@gmail.com>

arch/i386/lib/board.c

@@ -422,10 +422,10 @@ void hang (void)
 unsigned long do_go_exec (ulong (*entry)(int, char *[]), int argc, char *argv[])
 {
 	/*
-	 * TODO: Test this function - changed to fix compiler error.
-	 * Original code was:
-	 *   return (entry >> 1) (argc, argv);
-	 * with a comment about Nios function pointers are address >> 1
+	 * x86 does not use a dedicated register to pass the pointer
+	 * to the global_data
 	 */
+	argv[-1] = (char *)gd;
+
 	return (entry) (argc, argv);
 }