[media] rtl28xxu: increase failed I2C msg repeat count to 3

1 and 2 wasn't enough for mn88472 chip on Astrometa device,
so increase it to 3.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>