staging: usbip: stub_main.c: code cleanup

Remove match_find() and replace with get_busid_idx(); change
get_busid_priv(), add_match_busid(), and del_match_busid() to use
get_busid_idx(); and cleanup code in the other functions.

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