media: ddbridge: fix output buffer check

A 188 byte gap has to be left between the writer and the consumer. This
requires 2*188 bytes available to be able to write to the output buffers.
So, change ddb_output_free() to report free bytes according to this rule.

Picked up from the upstream dddvb-0.9.33 release.
Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/pci/ddbridge/ddbridge-core.c

@@ -572,12 +572,12 @@ static u32 ddb_output_free(struct ddb_output *output)
 
 	if (output->dma->cbuf != idx) {
 		if ((((output->dma->cbuf + 1) % output->dma->num) == idx) &&
-		    (output->dma->size - output->dma->coff <= 188))
+		    (output->dma->size - output->dma->coff <= (2 * 188)))
 			return 0;
 		return 188;
 	}
 	diff = off - output->dma->coff;
-	if (diff <= 0 || diff > 188)
+	if (diff <= 0 || diff > (2 * 188))
 		return 188;
 	return 0;
 }