USB: Make device reset stop retrying after disconnect

This patch (as898) changes the port reset code in the hub driver.  If
a connect change occurs, it is reported the same way as a disconnect
(which of course is what it really is).

It also changes usb_reset_device(), to prevent the routine from futilely
retrying the reset after a disconnect has occurred.

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