staging: usbip: stub_dev.c: move stub_driver definition and update driver name

Move the stub_driver definition to the end of file and, therefore,
remove foward declarations. Update driver name to usbip-host.

A few comments were slightly edited too.

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