dvb frontends: treat firmware data as const

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
diff --git a/drivers/media/dvb/frontends/sp887x.c b/drivers/media/dvb/frontends/sp887x.c
index 49f5587..4543609 100644
--- a/drivers/media/dvb/frontends/sp887x.c
+++ b/drivers/media/dvb/frontends/sp887x.c
@@ -140,7 +140,7 @@
 	u8 buf [BLOCKSIZE+2];
 	int i;
 	int fw_size = fw->size;
-	unsigned char *mem = fw->data;
+	const unsigned char *mem = fw->data;
 
 	dprintk("%s\n", __func__);