media: imx7-media-csi.c: fix merge breakage

Commit 5964cbd8 ("imx: Set capture compose rectangle in
capture_device_set_format") broke the compilation of commit
05f63404 ("staging/imx7: add imx7 CSI subdev driver").

These patches came in through different pull requests and
nobody noticed that the first changed functions that the
second relied upon.

Update imx7-media-csi.c accordingly.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>