[media] em28xx: tuner setup is broken after algo_data change

Commit aab3125c broke em28xx. I traced
this eventually to the change in what algo_data points to. This pointer
is also passed to em28xx_tuner_callback() through several hidden tuner
layers (yuck!) and that callback was not updated.
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/usb/em28xx/em28xx-cards.c

@@ -2229,8 +2229,9 @@ static unsigned short msp3400_addrs[] = {
 
 int em28xx_tuner_callback(void *ptr, int component, int command, int arg)
 {
+	struct em28xx_i2c_bus *i2c_bus = ptr;
+	struct em28xx *dev = i2c_bus->dev;
 	int rc = 0;
-	struct em28xx *dev = ptr;
 
 	if (dev->tuner_type != TUNER_XC2028 && dev->tuner_type != TUNER_XC5000)
 		return 0;