drm/exynos: exynos_dp: Apply of-display-mode-bridge to parse the display-timings...

drm/exynos: exynos_dp: Apply of-display-mode-bridge to parse the display-timings node

If there is neither a panel nor a bridge, the display timing can be
parsed from the display-timings node under the dp node.

In order to get rid of &analogix_dp_plat_data.get_modes() and make
the codes more consistent, apply DRM of-display-mode-bridge to parse
display timings.

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Heiko Stuebner <heiko@sntech.de> # rk3588
Link: https://patch.msgid.link/20260409065301.446670-6-damon.ding@rock-chips.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>