pinctrl: mscc: Fix multiple definition error

With gcc-11 we get a multiple errors here as the declarations for
mscc_pinctrl_ops and mscc_gpio_ops are missing an extern.

CC: Gregory CLEMENT <gregory.clement@bootlin.com>
Cc: Lars Povlsen <lars.povlsen@microchip.com>
Cc: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: NTom Rini <trini@konsulko.com>
Reviewed-by: NHoratiu Vultur <horatiu.vultur@microchip.com>
Reviewed-by: NDaniel Schwierzeck <daniel.schwierzeck@gmail.com>

drivers/pinctrl/mscc/mscc-common.h

@@ -61,6 +61,6 @@ int mscc_pinctrl_probe(struct udevice *dev, int num_func,
 		       const struct mscc_pin_data *mscc_pins, int num_pins,
 		       char * const *function_names,
 		       const unsigned long *mscc_gpios);
-const struct pinctrl_ops mscc_pinctrl_ops;
+extern const struct pinctrl_ops mscc_pinctrl_ops;
 
-const struct dm_gpio_ops mscc_gpio_ops;
+extern const struct dm_gpio_ops mscc_gpio_ops;