i2c: also convert placeholder function to return errno

All i2c_new_device-alike functions return ERR_PTR these days, but this
fallback function was missed.

Fixes: 2dea645f ("i2c: acpi: Return error pointers from i2c_acpi_new_device()")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[wsa: changed from 'ENOSYS' to 'ENODEV']
Signed-off-by: Wolfram Sang <wsa@kernel.org>