drm/amd/display: Set FixRate bit in VSIF V3

[Why]
Signal FreeSync display that we are in Fixed Rate mode, and
expand the FreeSync range to 1024.

[How]
Set the new bit in SB16:bit0, and augment the min and max
refresh rate with 2 extra bits.

Signed-off-by: AMD\ramini <Reza.Amini@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>