drm/bridge: cdns-dsi: Fix the _atomic_check()

drm/bridge: cdns-dsi: Fix the _atomic_check()

Use the "adjusted_mode" for the dsi configuration check, as that is the
more appropriate display_mode for validation, and later bridge enable.

Also, fix the mode_valid_check parameter from false to true, as the dsi
configuration check is taking place during the check-phase, and the
crtc_* mode values are not expected to be populated yet.

Fixes: a53d987756ea ("drm/bridge: cdns-dsi: Move DSI mode check to _atomic_check()")
Signed-off-by: Aradhya Bhatia <aradhya.bhatia@linux.dev>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Tested-by: Jayesh Choudhary <j-choudhary@ti.com>
Reviewed-by: Devarsh Thakkar <devarsht@ti.com>
Link: https://lore.kernel.org/r/20250723-cdns-dsi-impro-v5-1-e61cc06074c2@ideasonboard.com
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>