drm/amd/display: Allow DCN301 to clear update flags

commit 2d418e4f upstream.

[Why & How]
Not letting DCN301 to clear after surface/stream update results
in artifacts when switching between active overlay planes. The issue
is known and has been solved initially. See below:
(https://gitlab.freedesktop.org/drm/amd/-/issues/3441

)

Fixes: f354556e ("drm/amd/display: limit clear_update_flags t dcn32 and above")
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>