drm/imx: parallel-display: add legacy bridge Kconfig dependency

The driver now uses the legacy bridge helper code but can be configured
to get built without it:

ERROR: modpost: "devm_imx_drm_legacy_bridge" [drivers/gpu/drm/imx/ipuv3/parallel-display.ko] undefined!

Add the required dependency, same as in the ldb driver.

Fixes: f94b9707 ("drm/imx: parallel-display: switch to imx_legacy_bridge / drm_bridge_connector")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241015073004.4066457-1-arnd@kernel.org