V4L/DVB (8648): ivtv: improve CC support

- change the work-queue to a single threaded high prio workqueue
- use DMA instead of PIO for the sliced VBI data.
- remove some incorrect tests
- increase the internal VBI capture queue size for sliced VBI packets
- ignore duplicate VBI lines

With these changes it should finally be possible to get reliable closed
captions.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/ivtv/ivtv-driver.h b/drivers/media/video/ivtv/ivtv-driver.h
index ab287b4..2ceb522 100644
--- a/drivers/media/video/ivtv/ivtv-driver.h
+++ b/drivers/media/video/ivtv/ivtv-driver.h
@@ -251,6 +251,7 @@
 #define IVTV_F_I_DEC_PAUSED	   20 	/* the decoder is paused */
 #define IVTV_F_I_INITED		   21 	/* set after first open */
 #define IVTV_F_I_FAILED		   22 	/* set if first open failed */
+#define IVTV_F_I_WORK_INITED       23	/* worker thread was initialized */
 
 /* Event notifications */
 #define IVTV_F_I_EV_DEC_STOPPED	   28	/* decoder stopped event */