stm32/mphalport: Add mp_hal_pin_config_speed() to select GPIO speed.

It should be used after mp_hal_pin_config() or mp_hal_pin_config_alt().

ports/stm32/mphalport.c

@@ -171,3 +171,9 @@ bool mp_hal_pin_config_alt(mp_hal_pin_obj_t pin, uint32_t mode, uint32_t pull, u
     mp_hal_pin_config(pin, mode, pull, af->idx);
     return true;
 }
+
+void mp_hal_pin_config_speed(mp_hal_pin_obj_t pin_obj, uint32_t speed) {
+    GPIO_TypeDef *gpio = pin_obj->gpio;
+    uint32_t pin = pin_obj->pin;
+    gpio->OSPEEDR = (gpio->OSPEEDR & ~(3 << (2 * pin))) | (speed << (2 * pin));
+}

ports/stm32/mphalport.h

@@ -59,3 +59,4 @@ static inline mp_uint_t mp_hal_ticks_cpu(void) {
 void mp_hal_gpio_clock_enable(GPIO_TypeDef *gpio);
 void mp_hal_pin_config(mp_hal_pin_obj_t pin, uint32_t mode, uint32_t pull, uint32_t alt);
 bool mp_hal_pin_config_alt(mp_hal_pin_obj_t pin, uint32_t mode, uint32_t pull, uint8_t fn, uint8_t unit);
+void mp_hal_pin_config_speed(mp_hal_pin_obj_t pin_obj, uint32_t speed);