drm/amd/display: revert wait in pipelock

[why]
Previous workaround to prevent a vsync flip to be converted
to immediate flip is no longer needed, and is risky because
there are cases where it can result in infinite loop.

[how]
Remove wait loop (which is potentially infinite) before locking
pipe
Signed-off-by: Jun Lei <Jun.Lei@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Reviewed-by: Eric Yang <eric.yang2@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c

@@ -1103,17 +1103,6 @@ void dcn20_pipe_control_lock(
 	if (pipe->plane_state != NULL)
 		flip_immediate = pipe->plane_state->flip_immediate;
 
-	if (flip_immediate && lock) {
-		while (pipe->plane_res.hubp->funcs->hubp_is_flip_pending(pipe->plane_res.hubp))	{
-			udelay(1);
-		}
-
-		if (pipe->bottom_pipe != NULL)
-			while (pipe->bottom_pipe->plane_res.hubp->funcs->hubp_is_flip_pending(pipe->bottom_pipe->plane_res.hubp))	{
-				udelay(1);
-			}
-	}
-
 	/* In flip immediate and pipe splitting case, we need to use GSL
 	 * for synchronization. Only do setup on locking and on flip type change.
 	 */