drm/amd/display: increase timeout for dmif dealloc

In some use-cases, e.g. multiple 4K displays,
exisitng wait time for reg update of 30msec timed out
during mode setiing that sometimes resulted in system bad state
as we continue without waiting for registry update complete.
Increasing timeout to 35msec fixes that problem.

Signed-off-by: Roman Li <Roman.Li@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>