[media] ts2020: do not use i2c_transfer() on sleep()

There is no need to use bulk i2c_transfer() to write single register.
Use write register function instead.

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