pinctrl: st: Show correct pin direction also in GPIO mode

Until now ST's pinconf_dbg_show() call-back has displayed the PIO
alternate function direction, which is only relevant if a pin is
operating in an alternate function mode i.e not GPIO mode.  If a
pin is in GPIO mode its direction is both set and status is
obtained by a completely different/unrelated bunch of registers.

This change ensures that the correct pin direction is shown, even
if a pin is operating in GPIO mode.

Reported-by: Olivier Clergeaud <olivier.clergeaud@st.com>
Acked-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>