MIPS: Loongson fix name confict - MEM_RESERVED

MEM_RESERVED is used as a value of enum mem_type in include/linux/
edac.h. This will make failure to build for Loongson in some case:
for example with CONFIG_RAS enabled.

So here rename MEM_RESERVED to SYSTEM_RAM_RESERVED in Loongson code.

Signed-off-by: YunQiang Su <yunqiang.su@imgtec.com>
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Reviewed-by: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17724/


Signed-off-by: James Hogan <jhogan@kernel.org>