i2c: core: Unify the firmware node type check

i2c: core: Unify the firmware node type check

OF and ACPI currently are using asymmetrical APIs to check
for the firmware node type. Unify them by using is_*_node()
against struct fwnode_handle pointer.

Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>