i2c: xlp9xx: return ENXIO on slave address NACK

Fix the driver violation of the common practice to return
ENXIO error on a slave address NACK.

Signed-off-by: Dmitry Bazhenov <dmitry.bazhenov@auriga.com>
Signed-off-by: George Cherian <george.cherian@cavium.com>
Tested-by: dann frazier <dann.frazier@canonical.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>