stm: sdioio: remove unused code related to "SD Card detect pin"

.. this probably came from the examples that I studied at the beginning
of implementation.

The card detection feature is unused.  As a "detect pin" is not
sent from the shared-bindings, there is no way to get the correct pin
anyway.  Instead, if code needs to detect the insertion state it can
directly use the pin as GPIO in Python code.

Author: jepler

ports/stm/common-hal/sdioio/SDCard.c

@@ -148,16 +148,6 @@ void common_hal_sdioio_sdcard_construct(sdioio_sdcard_obj_t *self,
     GPIO_InitStruct.Pin = pin_mask(clock->number);
     HAL_GPIO_Init(pin_port(clock->port), &GPIO_InitStruct);
 
-// XXX hard coded pin
-#define SD_DETECT_PIN GPIO_PIN_12
-#define SD_DETECT_GPIO_PORT GPIOB
-
-    /*!< Configure SD_SPI_DETECT_PIN pin: SD Card detect pin */
-    GPIO_InitStruct.Pin = SD_DETECT_PIN;
-    GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
-    GPIO_InitStruct.Pull = GPIO_PULLUP;
-    HAL_GPIO_Init(SD_DETECT_GPIO_PORT, &GPIO_InitStruct);
-
     __HAL_RCC_SDIO_CLK_ENABLE();
 
     self->handle.Init.ClockDiv = SDIO_TRANSFER_CLK_DIV;