drm/bridge: ti-sn65dsi86: Fix multiple instances

Each bridge instance creates up to four auxiliary devices with different
names.  However, their IDs are always zero, causing duplicate filename
errors when a system has multiple bridges:

    sysfs: cannot create duplicate filename '/bus/auxiliary/devices/ti_sn65dsi86.gpio.0'

Fix this by using a unique instance ID per bridge instance.  The
instance ID is derived from the I2C adapter number and the bridge's I2C
address, to support multiple instances on the same bus.

Fixes: bf73537f ("drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/7a68a0e3f927e26edca6040067fb653eb06efb79.1733840089.git.geert+renesas@glider.be