V4L/DVB (4532): Isl6421: Release callback installed incorrectly

The release callback was installed in ops.release, it should have been
ops.release_sec.  This prevented to front-end release from getting
called.
Signed-off-by: NTrent Piepho <xyzzy@speakeasy.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/dvb/frontends/isl6421.c

@@ -126,7 +126,7 @@ struct dvb_frontend *isl6421_attach(struct dvb_frontend *fe, struct i2c_adapter
 	}
 
 	/* install release callback */
-	fe->ops.release = isl6421_release;
+	fe->ops.release_sec = isl6421_release;
 
 	/* override frontend ops */
 	fe->ops.set_voltage = isl6421_set_voltage;