staging: usbip: add userspace code

Add userspace code from svn trunk revision 175. Located at
https://usbip.svn.sourceforge.net/svnroot/usbip/linux/trunk/src

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