drm/imx: parallel-display: Prefer bus format set via legacy "interface-pix-fmt" DT...

drm/imx: parallel-display: Prefer bus format set via legacy "interface-pix-fmt" DT property

Prefer bus format set via legacy "interface-pix-fmt" DT property
over panel bus format. This is necessary to retain support for
DTs which configure the IPUv3 parallel output as 24bit DPI, but
connect 18bit DPI panels to it with hardware swizzling.

This used to work up to Linux 6.12, but stopped working in 6.13,
reinstate the behavior to support old DTs.

Cc: stable@vger.kernel.org
Fixes: 5f6e56d3319d ("drm/imx: parallel-display: switch to drm_panel_bridge")
Signed-off-by: Marek Vasut <marex@nabladev.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://patch.msgid.link/20260110171510.692666-1-marex@nabladev.com