drm/amd/display: Fix and simplify apply_below_the_range()

The comparison of inserted_frame_duration_in_us against a
duration calculated from max_refresh_in_uhz is both wrong
in its math and not needed, as the min_duration_in_us value
is already cached in in_out_vrr for reuse. No need to
recalculate it wrongly at each invocation.
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/modules/freesync/freesync.c

@@ -437,10 +437,8 @@ static void apply_below_the_range(struct core_freesync *core_freesync,
 			inserted_frame_duration_in_us = last_render_time_in_us /
 							frames_to_insert;
 
-		if (inserted_frame_duration_in_us <
-			(1000000 / in_out_vrr->max_refresh_in_uhz))
-			inserted_frame_duration_in_us =
-				(1000000 / in_out_vrr->max_refresh_in_uhz);
+		if (inserted_frame_duration_in_us < in_out_vrr->min_duration_in_us)
+			inserted_frame_duration_in_us = in_out_vrr->min_duration_in_us;
 
 		/* Cache the calculated variables */
 		in_out_vrr->btr.inserted_duration_in_us =