[MIPS] Fix a sparse warning in arch/mips/pci/pci.c

Fixes this warning:

arch/mips/pci/pci.c:284:18: warning: symbol 'dev' shadows an earlier one
arch/mips/pci/pci.c:272:17: originally declared here

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>