staging: usbip: replace usbip_u{dbg,err,info} and printk with dev_ and pr_

This switches all of the usbip_u{dbg,err,info} and printk statements to
dev_<level>, if possible, or pr_<level> macros. And removes a few
unnecessary debug statements.

Signed-off-by: matt mooney <mfm@muteddisk.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>