drm/amd/display: get tail pipe before aquire free pipe

[Why]
For some complicated blending transition cases, the head
pipe of the second stream may end up being a higher pipe
index than the free pipe.  In those cases dc_add_plane_to_context
will incorrectly set the tail_pipe to the free pipe, which
will cause the top_pipe and bottom_pipe to be the same

[How]
Move the call to resource_get_tail_pipe_for_stream() to be
before call to acquire_free_pipe_for_stream().
Signed-off-by: Eric Bernstein <eric.bernstein@amd.com>
Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@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/core/dc_resource.c

@@ -1182,6 +1182,9 @@ bool dc_add_plane_to_context(
 		return false;
 	}
 
+	tail_pipe = resource_get_tail_pipe_for_stream(&context->res_ctx, stream);
+	ASSERT(tail_pipe);
+
 	free_pipe = acquire_free_pipe_for_stream(context, pool, stream);
 
 #if defined(CONFIG_DRM_AMD_DC_DCN1_0)
@@ -1199,10 +1202,6 @@ bool dc_add_plane_to_context(
 	free_pipe->plane_state = plane_state;
 
 	if (head_pipe != free_pipe) {
-
-		tail_pipe = resource_get_tail_pipe_for_stream(&context->res_ctx, stream);
-		ASSERT(tail_pipe);
-
 		free_pipe->stream_res.tg = tail_pipe->stream_res.tg;
 		free_pipe->stream_res.abm = tail_pipe->stream_res.abm;
 		free_pipe->stream_res.opp = tail_pipe->stream_res.opp;