drm/amdgpu/display: change pipe policy for DCN 2.1

Fixes crash on MST Hub disconnect.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1849
Fixes: ee2698cf ("drm/amd/display: Changed pipe split policy to allow for multi-display pipe split")
Signed-off-by: Benjamin Marty <info@benjaminmarty.ch>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c

@@ -644,7 +644,7 @@ static const struct dc_debug_options debug_defaults_drv = {
 		.clock_trace = true,
 		.disable_pplib_clock_request = true,
 		.min_disp_clk_khz = 100000,
-		.pipe_split_policy = MPC_SPLIT_DYNAMIC,
+		.pipe_split_policy = MPC_SPLIT_AVOID_MULT_DISP,
 		.force_single_disp_pipe_split = false,
 		.disable_dcc = DCC_ENABLE,
 		.vsr_support = true,