drm/bridge: ti-sn65dsi86: Check bridge connection failure

Read out and check the ID registers, so we can bail out if I2C
communication does not work or if the device is unknown. Tested on a
Renesas GrayHawk board (R-Car V4M) by using a wrong I2C address and by
not enabling RuntimePM for the device.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20250318155549.19625-2-wsa+renesas@sang-engineering.com