staging: usbip: Fix man-pages for usbip userspace utilities

The usbip userspace utilities contained some half-documented (only in
--help, not in man) options. They were added to the man-pages of usbip
and usbipd.
Also a typo in the usbip headline was fixed.

Signed-off-by: Tobias Polzer <tobias.polzer@fau.de>
Signed-off-by: Dominik Paulus <dominik.paulus@fau.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>