media: nxp: imx8-isi: Keep the default value for BLANK_PXL field

media: nxp: imx8-isi: Keep the default value for BLANK_PXL field

The field BLANK_PXL provides the value of the blank pixel to be inserted
in the image in case an overflow error occurs in the output buffers of
the channel. Its default value is 0xff, so no need to set again.

Besides, the field only exist in i.MX8QM/XP ISI version. Other versions
like i.MX 8M series, remove the field since it won't send data to AXI bus
when overflow error occurs and mark BLANK_PXL as reserved. i.MX9 series
use it for other purposes.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Guoniu Zhou <guoniu.zhou@nxp.com>
Link: https://patch.msgid.link/20251105-isi_imx95-v3-2-3987533cca1c@nxp.com
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>