When DML2 was introduced, it targeted only new DCN versions. For
controlling which ASIC should use this new version of DML, it was
introduced the using_dml2 attribute. To avoid ambiguities, this commit
explicitly sets using_dml2 to false in all ASICs that do not support
DML2.

Cc: Vitaly Prosyak <vprosyak@amd.com>
Cc: Roman Li <roman.li@amd.com>
Cc: Qingqing Zhuo <Qingqing.Zhuo@amd.com>
Cc: Daniel Wheeler <daniel.wheeler@amd.com>
Cc: Alex Deucher <Alexander.Deucher@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>