pinctrl: Fix usage of PINCTRL_DT_DEFINE with C++

Using PINCTRL_DT_DEFINE from a C++ file cause a
"designator order field" error.
This updates Z_PINCTRL_STATE_INIT to respect the same order as
defined in struct pinctrl_state.

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>