usb: host: Replace empty define with do while

It's dangerous to use empty code define.
Furthermore it lead to the following warning:
"suggest braces around empty body in an « else » statement"

So let's replace emptyness by "do {} while(0)"

Furthermore, as suggested by Joe Perches, rename the macro to INCR.

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>