MIPS: IP27: Fix GCC 4.6.0 build error.

  CC      arch/mips/sgi-ip27/ip27-hubio.o
arch/mips/sgi-ip27/ip27-hubio.c: In function 'hub_pio_map':
arch/mips/sgi-ip27/ip27-hubio.c:32:20: error: variable 'junk' set but not used [-Werror=unused-but-set-variable]
cc1: all warnings being treated as errors

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