MAINTAINERS: correct file entry in MEDIA DRIVERS FOR FREESCALE IMX7/8

Commit cd063027 ("media: imx: Unstage the imx8mq-mipi-csi2 driver")
adds a file entry for the driver code to MEDIA DRIVERS FOR FREESCALE
IMX7/8, but misses the number '2' suffix in that entry. Hence,
./scripts/get_maintainer.pl --self-test=patterns complains about a broken
reference.

Correct the file entry in MEDIA DRIVERS FOR FREESCALE IMX7/8.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>