drm/amd/display: dce_audio: add DCE6 specific macros,functions

[Why]
DCE6 has no DCCG_AUDIO_DTO2_USE_512FBR_DTO mask in DCCG_AUDIO_DTO_SOURCE register

[How]
Add DCE6 specific macros definitions for AUD masks
DCE6 AUD macros will avoid buiding errors when using DCE6 headers
Add dce60_aud_wall_dto_setup() w/o 512*Fs programming
Use dce60_aud_wall_dto_setup() in dce60_funcs
Add DCE specific dce60_audio_create

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>