media: staging/imx: always select VIDEOBUF2_DMA_CONTIG

I ran into a rare build error during randconfig testing:

drivers/staging/media/imx/imx-media-capture.o: In function `capture_stop_streaming':
imx-media-capture.c:(.text+0x224): undefined reference to `vb2_buffer_done'
drivers/staging/media/imx/imx-media-capture.o: In function `imx_media_capture_device_register':
imx-media-capture.c:(.text+0xe60): undefined reference to `vb2_queue_init'
imx-media-capture.c:(.text+0xfa0): undefined reference to `vb2_dma_contig_memops'

While VIDEOBUF2_DMA_CONTIG was already selected by the camera driver,
it wasn't necessarily there with just the base driver enabled.
This moves the 'select' statement to the top-level option to make
sure it's always available.

Fixes: 64b5a49df486 ("[media] media: imx: Add Capture Device Interface")

Signed-off-by: Arnd Bergmann <[e-mail]>
Reviewed-by: Steve Longerbeam <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/staging/media/imx/Kconfig

···
 	tristate "i.MX5/6 V4L2 media core driver"
 	depends on MEDIA_CONTROLLER && VIDEO_V4L2 && ARCH_MXC && IMX_IPUV3_CORE
 	depends on VIDEO_V4L2_SUBDEV_API
+	select VIDEOBUF2_DMA_CONTIG
 	select V4L2_FWNODE
 	---help---
 	  Say yes here to enable support for video4linux media controller
···
 config VIDEO_IMX_CSI
 	tristate "i.MX5/6 Camera Sensor Interface driver"
 	depends on VIDEO_IMX_MEDIA && VIDEO_DEV && I2C
-	select VIDEOBUF2_DMA_CONTIG
 	default y
 	---help---
 	  A video4linux camera sensor interface driver for i.MX5/6.