gpio: sim: Use %pfwP specifier instead of calling fwnode API directly

Instead of calling fwnode_get_name() and supply as %s, use %pfwP which
will do the same inside printf() call.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>