Fix return value of mtest when CFG_ALT_MEMTEST set

Fix a missing return statement from a non-void function.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
diff --git a/common/cmd_mem.c b/common/cmd_mem.c
index a994211..5fce773 100644
--- a/common/cmd_mem.c
+++ b/common/cmd_mem.c
@@ -659,6 +659,7 @@
 	vu_long	*addr, *start, *end;
 	ulong	val;
 	ulong	readback;
+	int     rcode = 0;
 
 #if defined(CFG_ALT_MEMTEST)
 	vu_long	addr_mask;
@@ -689,7 +690,6 @@
 #else
 	ulong	incr;
 	ulong	pattern;
-	int     rcode = 0;
 #endif
 
 	if (argc > 1) {
@@ -954,8 +954,8 @@
 		}
 		incr = -incr;
 	}
-	return rcode;
 #endif
+	return rcode;
 }