pinctrl: st: activate strict mux mode

This activates strict mode muxing for the ST pin controllers,
as these do not allow GPIO and functions to use the same pin
simultaneously.
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-st.c

@@ -985,6 +985,7 @@ static struct pinmux_ops st_pmxops = {
 	.get_function_groups	= st_pmx_get_groups,
 	.set_mux		= st_pmx_set_mux,
 	.gpio_set_direction	= st_pmx_set_gpio_direction,
+	.strict			= true,
 };
 
 /* Pinconf  */