MIPS: OCTEON: octeon-usb: Use devm_platform_get_and_ioremap_resource()

Remove unneeded error handling on the result of a call
to platform_get_resource() when the value is passed to
devm_ioremap_resource().

And use devm_platform_get_and_ioremap_resource() to simplify
code.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>