ia32: Remove unnecessary Proj from prefetch nodes.

They all have a single memory result.

ir/be/ia32/ia32_spec.pl

@@ -270,6 +270,7 @@ my $prefetchop = {
 	state     => "exc_pinned",
 	in_reqs   => [ "gp", "gp", "mem" ],
 	out_reqs  => [ "mem" ],
+	mode      => mode_M,
 	ins       => [ "base", "index", "mem" ],
 	outs      => [ "M" ],
 };

ir/be/ia32/ia32_transform.c

@@ -5264,8 +5264,7 @@ static ir_node *gen_prefetch(ir_node *node)
 	set_address(new_node, &addr);
 
 	SET_IA32_ORIG_NODE(new_node, node);
-
-	return be_new_Proj(new_node, pn_ia32_Prefetch_M);
+	return new_node;
 }
 
 /**