pinctrl: don't fall back to pinctrl_select_state_simple()

If CONFIG_PINCTRL_FULL is enabled, never fall back to the simple
implementation. pinctrl_select_state() is called for each device and it
is expected to fail. A fallback to the simple imeplementation doesn't
make much sense.

To keep the return code consistent, we need to change the -EINVAL (which
was ignored before) to -ENOSYS.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>