[media] tw686x: make const structs static

Fix sparse warnings:

tw686x-video.c:148:29: warning: symbol 'memcpy_dma_ops' was not declared. Should it be static?
tw686x-video.c:195:29: warning: symbol 'contig_dma_ops' was not declared. Should it be static?
tw686x-video.c:361:29: warning: symbol 'sg_dma_ops' was not declared. Should it be static?
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/pci/tw686x/tw686x-video.c

@@ -145,7 +145,7 @@ static void tw686x_memcpy_buf_refill(struct tw686x_video_channel *vc,
 	vc->curr_bufs[pb] = NULL;
 }
 
-const struct tw686x_dma_ops memcpy_dma_ops = {
+static const struct tw686x_dma_ops memcpy_dma_ops = {
 	.alloc		= tw686x_memcpy_dma_alloc,
 	.free		= tw686x_memcpy_dma_free,
 	.buf_refill	= tw686x_memcpy_buf_refill,
@@ -177,7 +177,7 @@ static void tw686x_contig_buf_refill(struct tw686x_video_channel *vc,
 	vc->curr_bufs[pb] = NULL;
 }
 
-const struct tw686x_dma_ops contig_dma_ops = {
+static const struct tw686x_dma_ops contig_dma_ops = {
 	.buf_refill	= tw686x_contig_buf_refill,
 	.mem_ops	= &vb2_dma_contig_memops,
 	.hw_dma_mode	= TW686X_FRAME_MODE,
@@ -330,7 +330,7 @@ static int tw686x_sg_setup(struct tw686x_dev *dev)
 	return 0;
 }
 
-const struct tw686x_dma_ops sg_dma_ops = {
+static const struct tw686x_dma_ops sg_dma_ops = {
 	.setup		= tw686x_sg_setup,
 	.alloc		= tw686x_sg_dma_alloc,
 	.free		= tw686x_sg_dma_free,