Use the GPIO config symbol to only build Au1000 interrupt code on chips with
compatible hw.
Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/670/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>