The Lontium DRM bridge drivers use mipi_dsi_() function interfaces so
they need to select DRM_MIPI_DSI to prevent build errors.

ERROR: modpost: "mipi_dsi_attach" [drivers/gpu/drm/bridge/lontium-lt9611uxc.ko] undefined!
ERROR: modpost: "mipi_dsi_device_register_full" [drivers/gpu/drm/bridge/lontium-lt9611uxc.ko] undefined!
ERROR: modpost: "of_find_mipi_dsi_host_by_node" [drivers/gpu/drm/bridge/lontium-lt9611uxc.ko] undefined!
ERROR: modpost: "mipi_dsi_device_unregister" [drivers/gpu/drm/bridge/lontium-lt9611uxc.ko] undefined!
ERROR: modpost: "mipi_dsi_detach" [drivers/gpu/drm/bridge/lontium-lt9611uxc.ko] undefined!
ERROR: modpost: "mipi_dsi_attach" [drivers/gpu/drm/bridge/lontium-lt9611.ko] undefined!
ERROR: modpost: "mipi_dsi_device_register_full" [drivers/gpu/drm/bridge/lontium-lt9611.ko] undefined!
ERROR: modpost: "of_find_mipi_dsi_host_by_node" [drivers/gpu/drm/bridge/lontium-lt9611.ko] undefined!
ERROR: modpost: "mipi_dsi_device_unregister" [drivers/gpu/drm/bridge/lontium-lt9611.ko] undefined!
ERROR: modpost: "mipi_dsi_detach" [drivers/gpu/drm/bridge/lontium-lt9611.ko] undefined!
WARNING: modpost: suppressed 5 unresolved symbol warnings because there were too many)

Fixes: 23278bf5 ("drm/bridge: Introduce LT9611 DSI to HDMI bridge")
Fixes: 0cbbd5b1 ("drm: bridge: add support for lontium LT9611UXC bridge")
Fixes: 30e2ae94 ("drm/bridge: Introduce LT8912B DSI to HDMI bridge")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Adren Grassein <adrien.grassein@gmail.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Vinod Koul <vkoul@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Adrien Grassein <adrien.grassein@gmail.com>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Robert Foss <robert.foss@linaro.org>
Cc: dri-devel@lists.freedesktop.org
Cc: stable@vger.kernel.org
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210415183639.1487-1-rdunlap@infradead.org