pinctrl: ssbi-mpp: constify copied structure

The pm8xxx_pinctrl_desc structure is only copied into another structure,
so make it const.

The opportunity for this change was found using Coccinelle.
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>

Link: https://lore.kernel.org/r/1577864614-5543-9-git-send-email-Julia.Lawall@inria.frSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/qcom/pinctrl-ssbi-mpp.c

@@ -430,7 +430,7 @@ static const struct pinconf_ops pm8xxx_pinconf_ops = {
 	.pin_config_group_set = pm8xxx_pin_config_set,
 };
 
-static struct pinctrl_desc pm8xxx_pinctrl_desc = {
+static const struct pinctrl_desc pm8xxx_pinctrl_desc = {
 	.name = "pm8xxx_mpp",
 	.pctlops = &pm8xxx_pinctrl_ops,
 	.pmxops = &pm8xxx_pinmux_ops,