Revert "drivers: gpio: STM32U5 independant IO supply"

This is already fixed in zephyrproject-rtos/hal_stm32#147.

This reverts commit 5b4ad9127f.

Signed-off-by: Maciej Zagrabski <mzi@trackunit.com>

drivers/gpio/gpio_stm32.c

@@ -711,11 +711,7 @@ static int gpio_stm32_init(const struct device *dev)
 	z_stm32_hsem_lock(CFG_HW_RCC_SEMID, HSEM_LOCK_DEFAULT_RETRY);
 	/* Port G[15:2] requires external power supply */
 	/* Cf: L4/L5 RM, Chapter "Independent I/O supply rail" */
-#if defined(CONFIG_SOC_SERIES_STM32U5X)
-	LL_PWR_EnableVDDIO2();
-#else
 	LL_PWR_EnableVddIO2();
-#endif
 	z_stm32_hsem_unlock(CFG_HW_RCC_SEMID);
 #endif
 	/* enable port clock (if runtime PM is not enabled) */