drm/bridge: ti-sn65dsi86: Enable HPD polling if IRQ is not used

drm/bridge: ti-sn65dsi86: Enable HPD polling if IRQ is not used

Fallback to polling to detect hotplug events on systems without
interrupts.

On systems where the interrupt line of the bridge is not connected,
the bridge cannot notify hotplug events. Only add the
DRM_BRIDGE_OP_HPD flag if an interrupt has been registered
otherwise remain in polling mode.

Fixes: 55e8ff842051 ("drm/bridge: ti-sn65dsi86: Add HPD for DisplayPort connector type")
Cc: stable@vger.kernel.org # 6.16: 9133bc3f0564: drm/bridge: ti-sn65dsi86: Add
Signed-off-by: Franz Schnyder <franz.schnyder@toradex.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
[dianders: Adjusted Fixes/stable line based on discussion]
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patch.msgid.link/20260206123758.374555-1-fra.schnyder@gmail.com