[WHY]
There can be a conflict between OS HDR multiplier and 3dlut HDR
multiplier, which are both sent to DC.

[HOW]
Instead of having dc determine which HDR multiplier to use, make the
decision in dm and send only the intended value in a surface update.
Store the current OS HDR multiplier and determine whether to use it or
the 3dlut's multiplier before sending the surface update to dc. Send
multiplier to dc in fixed31_32 format, dc then converts it to hw format.
Signed-off-by: Michael Strauss <michael.strauss@amd.com>
Reviewed-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>