Let's look at the irq status bits after a transfer and see if we got a
nack or a defer or a timeout, instead of telling drm layers that
everything was fine, while still printing an error message. I wasn't
sure about NACK+DEFER so I lumped all those various errors along with a
nack so that the drm core can figure out that things are just not going
well. The important thing is that we're now returning -ETIMEDOUT when
the message times out and nacks for bad addresses.

Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Abhinav Kumar <abhinavk@codeaurora.org>
Cc: Kuogee Hsieh <khsieh@codeaurora.org>
Cc: aravindh@codeaurora.org
Cc: Sean Paul <sean@poorly.run>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Kuogee Hsieh <khsieh@codeaurora.org>
Link: https://lore.kernel.org/r/20210507212505.1224111-4-swboyd@chromium.orgSigned-off-by: Rob Clark <robdclark@chromium.org>