MIPS: JZ4740: Add setup code

Add plat_mem_setup and get_system_type for JZ4740 SoCs.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/1399/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>