DSR-1000N board has two GPIO LEDs next to USB ports. Add support for them.

[ralf@linux-mips.org: Resolved conflict due to the moving of the DTS files
into vendor subdirectories.]
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9624/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>