USB: ci13xxx_udc: Mark request dma address as invalid in ep_nuke

When a request is allocated its dma address is marked as invalid
by the controller driver.  If function drivers does not modify
it, controller driver takes the responsibility of mapping and
un-mapping the buffer.  Controller driver also mark the dma address
as invalid after a request is completed or dequeued so that
it is ready for the next transfer when queued by the function driver.

When an endpoint is disabled, all the pending requests are nuked but
dma address is not marked as invalid.  If the function driver use the
same request, controller driver does not map the buffer before giving
it dma which results in data corruption.

Change-Id: Iadb5fd533cba5c55c833e831a0be82146772a521
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>