drm/vc4: hdmi: stop rereading EDID in get_modes()

The vc4_hdmi_connector_detect_ctx() via vc4_hdmi_handle_hotplug()
already reads EDID and propagates it to the drm_connector. Stop
rereading EDID as a part of the .get_modes() callback and just update
the list of modes. This matches the behaviour of the i915 driver.

Acked-by: Maxime Ripard <mripard@kernel.org>
Tested-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241224-drm-bridge-hdmi-connector-v10-9-dc89577cd438@linaro.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>