[Why]
This change is needed for DCN2 to make use of the immediate_update
flag. With this flag, update to PPS will be immediate, rather than
always taking place on dig_update signal.

[How]
Set AFMT_GENERIC7_FRAME/IMMEDIATE_UPDATE bits depending on flag
value.
Reviewed-by: NWenjing Liu <wenjing.liu@amd.com>
Acked-by: NAnson Jacob <Anson.Jacob@amd.com>
Signed-off-by: NIlya <Ilya.Bakoulin@amd.com>
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>