drm/amd/display: Fix ASIC check in aux timeout workaround

[Why]
Aux write was meant to be ASIC specific, and is
causing compliance failures on newer parts.

[How]
Make workaround specific to single ASIC.

Reviewed-by: Michael Strauss <michael.strauss@amd.com>
Acked-by: Alan Liu <haoping.liu@amd.com>
Signed-off-by: Taimur Hassan <syed.hassan@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>