[PATCH] USB: USB API documentation modification

In response to complaints about excessive latency in the uhci-hcd driver
I'm planning to convert it to a top-half/bottom-half design.  It turns out
that to do this, the USB API has to be modified slightly since the driver
will not be able to meet one of the guarantees in the current API.  This
patch changes some kerneldoc, specifying the weaker guarantee.

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