V4L/DVB (8745): v4l2: fix a bunch of compile warnings.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/btcx-risc.c b/drivers/media/video/btcx-risc.c
index 3324ab3..ac1b268 100644
--- a/drivers/media/video/btcx-risc.c
+++ b/drivers/media/video/btcx-risc.c
@@ -64,7 +64,7 @@
 		       unsigned int size)
 {
 	__le32 *cpu;
-	dma_addr_t dma;
+	dma_addr_t dma = 0;
 
 	if (NULL != risc->cpu && risc->size < size)
 		btcx_riscmem_free(pci,risc);