MIPS: add BMIPS Comtrend AR-5315u board

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>

include/configs/comtrend_ar5315u.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (C) 2018 Álvaro Fernández Rojas <noltari@gmail.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <configs/bmips_common.h>
+#include <configs/bmips_bcm6318.h>
+
+#define CONFIG_REMAKE_ELF
+
+#define CONFIG_ENV_SIZE			(8 * 1024)
+
+#define CONFIG_AUTO_COMPLETE
+#define CONFIG_CMDLINE_EDITING
+#define CONFIG_SYS_LONGHELP