staging: usbip: userspace: usbip_host: update function and variable names

Officially change stub_driver to usbip_host_driver. And, reorganize
usbip_host_driver.c while also cleaning up coding style.

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