pinctrl: st: Annotate st_pinconf_dbg_show() as holding mutex

st_pinconf_dbg_show() unlocks and locks the pinctrl_dev mutex, so it
must be called by the pinctrl core with the mutex hold.  Annotate the
function with sparse __must_hold, so any changes in pinctrl locking will
be statically detected.

Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>

Author: krzk

drivers/pinctrl/pinctrl-st.c

@@ -987,6 +987,7 @@ static int st_pinconf_get(struct pinctrl_dev *pctldev,
 
 static void st_pinconf_dbg_show(struct pinctrl_dev *pctldev,
 				   struct seq_file *s, unsigned pin_id)
+	__must_hold(&pctldev->mutex)
 {
 	struct st_pio_control *pc;
 	unsigned long config;