drm/msm/gpu: Fix idle_work time

This was supposed to be a relative timer, not absolute.

Fixes: 658f4c82 ("drm/msm/devfreq: Add 1ms delay before clamping freq")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20211120200103.1051459-1-robdclark@gmail.com


Signed-off-by: Rob Clark <robdclark@chromium.org>