i2c: mv64xxx: Fix transfer error code

The driver returns -ENODEV as error code if it did not get an ACK
from the device. Per Documentation/i2c/fault-codes, it should
return -ENXIO.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>