media: soc_camera: Remove leftover files, add TODO

Remove a few files left over from the mt9t031 driver. While at it, add a
TODO file for the SoC camera framework as a whole.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/staging/media/mt9t031/Kconfig

-config SOC_CAMERA_MT9T031
-	tristate "mt9t031 support (DEPRECATED)"
-	depends on SOC_CAMERA && I2C
-	help
-	  This driver supports MT9T031 cameras from Micron.

drivers/staging/media/mt9t031/Makefile

-obj-$(CONFIG_SOC_CAMERA_MT9T031)		+= mt9t031.o

drivers/staging/media/mt9t031/TODO

-This sensor driver needs to be converted to a regular
-v4l2 subdev driver. The soc_camera framework is deprecated and
-will be removed in the future. Unless someone does this work this
-sensor driver will be deleted when the soc_camera framework is
-deleted.

drivers/staging/media/soc_camera/TODO

+The SoC camera framework is obsolete and scheduled for removal in the near
+future. Developers are encouraged to convert the drivers to use the
+regular V4L2 API if these drivers are still needed (and if someone has the
+hardware).