drm/amd/display: Clear state after exiting fixed active VRR state

[why]
Upon exiting a fixed active VRR state, the state isn't cleared. This
leads to the variable VRR range to be calculated incorrectly.

[how]
Set fixed active state to false when updating vrr params

Signed-off-by: Amanda Liu <amanda.liu@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>