MIPS: OCTEON: octeon-usb: Consolidate error messages

Console output currently looks like USB clocks initialized succesfully
even in case of error. Fix that and use consistently dev_err for fatal
errors otherwise dev_warn.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>