drm/rockchip: dsi: Force synchronous probe

We can't safely probe a dual-DSI display asynchronously
(driver_async_probe='*' or driver_async_probe='dw-mipi-dsi-rockchip'
cmdline), because dw_mipi_dsi_rockchip_find_second() pokes one DSI
device's drvdata from the other device without any locking.

Request synchronous probe, at least until this driver learns some
appropriate locking for dual-DSI initialization.

Cc: <stable@vger.kernel.org>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20221019170255.2.I6b985b0ca372b7e35c6d9ea970b24bcb262d4fc1@changeid

drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c

@@ -1689,5 +1689,11 @@ struct platform_driver dw_mipi_dsi_rockchip_driver = {
 		.of_match_table = dw_mipi_dsi_rockchip_dt_ids,
 		.pm	= &dw_mipi_dsi_rockchip_pm_ops,
 		.name	= "dw-mipi-dsi-rockchip",
+		/*
+		 * For dual-DSI display, one DSI pokes at the other DSI's
+		 * drvdata in dw_mipi_dsi_rockchip_find_second(). This is not
+		 * safe for asynchronous probe.
+		 */
+		.probe_type = PROBE_FORCE_SYNCHRONOUS,
 	},
 };