stm32/main: Don't unconditionally enable GPIO A,B,C,D clocks.

Rely on them being enabled only when needed.

Signed-off-by: Damien George <damien@micropython.org>

ports/stm32/main.c

@@ -369,14 +369,6 @@ void stm32_main(uint32_t reset_mode) {
     // set the system clock to be HSE
     SystemClock_Config();
 
-    // enable GPIO clocks
-    __HAL_RCC_GPIOA_CLK_ENABLE();
-    __HAL_RCC_GPIOB_CLK_ENABLE();
-    __HAL_RCC_GPIOC_CLK_ENABLE();
-    #if defined(GPIOD)
-    __HAL_RCC_GPIOD_CLK_ENABLE();
-    #endif
-
     #if defined(STM32F4) || defined(STM32F7)
     #if defined(__HAL_RCC_DTCMRAMEN_CLK_ENABLE)
     // The STM32F746 doesn't really have CCM memory, but it does have DTCM,