ARM: dts: stm32: fix stusb1600 pinctrl used on stm32mp157c-dk

A pinctrl handle is used to setup a pull-up on the stusb1600 IRQ pin (that
is open drain).
When in ANALOG state, no pull-up can be applied in the GPIO HW controller,
still the setting is done into the register. The pull-up is effective
currently, only when the GPIO IRQ is requested. The correct setting is to
use directly the GPIO, instead of ANALOG state.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

arch/arm/boot/dts/stm32mp15-pinctrl.dtsi

@@ -1718,7 +1718,7 @@
 
 	stusb1600_pins_a: stusb1600-0 {
 		pins {
-			pinmux = <STM32_PINMUX('I', 11, ANALOG)>;
+			pinmux = <STM32_PINMUX('I', 11, GPIO)>;
 			bias-pull-up;
 		};
 	};