drm/imx: parallel-display: drop edid override support

drm/imx: parallel-display: drop edid override support

None of the in-kernel DT files ever used edid override with the
fsl-imx-drm driver. In case the EDID needs to be specified manually, DRM
core allows one to either override it via the debugfs or to load it via
request_firmware by using DRM_LOAD_EDID_FIRMWARE. In all other cases
EDID and/or modes are to be provided as a part of the panel driver.

Drop support for the edid property.

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Tested-by: Chris Healy <cphealy@gmail.com>
Tested-by: Philipp Zabel <p.zabel@pengutronix.de> # on imx6q-nitrogen6x
Link: https://patchwork.freedesktop.org/patch/msgid/20240602-drm-imx-cleanup-v3-4-e549e2a43100@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>