USB: simplify the interface of usb_get_status()

This patch simplifies the interface presented by usb_get_status().
Instead of forcing callers to check for the proper data length and
convert the status value to host byte order, the function will now
do these things itself.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>