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>

include/linux/i2c.h

@@ -1001,7 +1001,7 @@ static inline u32 i2c_acpi_find_bus_speed(struct device *dev)
 static inline struct i2c_client *i2c_acpi_new_device(struct device *dev,
 					int index, struct i2c_board_info *info)
 {
-	return NULL;
+	return ERR_PTR(-ENODEV);
 }
 static inline struct i2c_adapter *i2c_acpi_find_adapter_by_handle(acpi_handle handle)
 {