V4L/DVB (8906): v4l-dvb: fix assorted sparse warnings

Fix sparse warnings. None are serious, but cutting down on these helps find
future serious sparse warnings/errors.

Redid the av7710.c patch based on a suggestion by Oliver Endriss.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/dvb/frontends/cx24110.h b/drivers/media/dvb/frontends/cx24110.h
index 1792adb..fdcceee 100644
--- a/drivers/media/dvb/frontends/cx24110.h
+++ b/drivers/media/dvb/frontends/cx24110.h
@@ -33,12 +33,17 @@
 	u8 demod_address;
 };
 
-static inline int cx24110_pll_write(struct dvb_frontend *fe, u32 val) {
-	int r = 0;
-	u8 buf[] = {(u8) (val>>24), (u8) (val>>16), (u8) (val>>8)};
+static inline int cx24110_pll_write(struct dvb_frontend *fe, u32 val)
+{
+	u8 buf[] = {
+		(u8)((val >> 24) & 0xff),
+		(u8)((val >> 16) & 0xff),
+		(u8)((val >> 8) & 0xff)
+	};
+
 	if (fe->ops.write)
-		r = fe->ops.write(fe, buf, 3);
-	return r;
+		return fe->ops.write(fe, buf, 3);
+	return 0;
 }
 
 #if defined(CONFIG_DVB_CX24110) || (defined(CONFIG_DVB_CX24110_MODULE) && defined(MODULE))