usbcore: trivial whitespace fixes

This patch (as844) makes some trivial whitespace fixes to a few files
in usbcore.  Oliver did most of the work and Alan added some tidying up.

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