MIPS: pci: convert to devm_ioremap_resource()

Convert all uses of devm_request_and_ioremap() to the newly introduced
devm_ioremap_resource() which provides more consistent error handling.

Signed-off-by: Silviu-Mihai Popescu <silviupopescu1990@gmail.com>
Patchwork: http://patchwork.linux-mips.org/patch/4986/


Acked-by: John Crispin <blogic@openwrt.org>