media: videobuf2: Add VIDEOBUF2_V4L2 Kconfig option for VB2 V4L2 part

Videobuf2 is now separate from V4L2 and can be now built without it, at
least in principle --- enabling videobuf2 in kernel configuration attempts
to compile videobuf2-v4l2.c but that will fail if CONFIG_VIDEO_V4L2 isn't
enabled.

Solve this by adding a separate Kconfig option for videobuf2-v4l2 and make
it a separate module as well. This means that drivers now need to choose
both the appropriate videobuf2 memory type
(VIDEOBUF2_{VMALLOC,DMA_CONTIG,DMA_SG}) and VIDEOBUF2_V4L2 if they need
both.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/common/videobuf2/Kconfig

@@ -3,6 +3,9 @@ config VIDEOBUF2_CORE
 	select DMA_SHARED_BUFFER
 	tristate
 
+config VIDEOBUF2_V4L2
+	tristate
+
 config VIDEOBUF2_MEMOPS
 	tristate
 	select FRAME_VECTOR

drivers/media/common/videobuf2/Makefile

@@ -1,5 +1,6 @@
 
-obj-$(CONFIG_VIDEOBUF2_CORE) += videobuf2-core.o videobuf2-v4l2.o
+obj-$(CONFIG_VIDEOBUF2_CORE) += videobuf2-core.o
+obj-$(CONFIG_VIDEOBUF2_V4L2) += videobuf2-v4l2.o
 obj-$(CONFIG_VIDEOBUF2_MEMOPS) += videobuf2-memops.o
 obj-$(CONFIG_VIDEOBUF2_VMALLOC) += videobuf2-vmalloc.o
 obj-$(CONFIG_VIDEOBUF2_DMA_CONTIG) += videobuf2-dma-contig.o