i2c: i801: convert to use i2c_new_client_device()

Move away from the deprecated API and return the shiny new ERRPTR where
useful.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>