Enable i2c read requests.

I2C read fix (necessary e.g. for mxl5007t tuner, because it
sends a 2 bytes for a read request, thus msg[0].len != msg[1].len).
Signed-off-by: Hans-Frieder Vogt <hfvogt@gmx.net>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>