ports/stm32/boards: Configure Arduino Portenta ETH DMA buffer sections.

Signed-off-by: Kwabena W. Agyeman <kwagyeman@live.com>

Author: kwagyeman

ports/stm32/boards/ARDUINO_PORTENTA_H7/mpconfigboard.h

@@ -325,6 +325,8 @@ extern struct _spi_bdev_t spi_bdev;
 #define MICROPY_HW_ETH_RMII_TXD0    (pin_G13)
 #define MICROPY_HW_ETH_RMII_TXD1    (pin_G12)
 
+#define MICROPY_HW_ETH_DMA_ATTR_SECTION         __attribute__((section(".dma_buffer")))
+
 #define MICROPY_HW_USB_VID                      0x2341
 #define MICROPY_HW_USB_PID                      0x045B
 #define MICROPY_HW_USB_PID_CDC_MSC              (MICROPY_HW_USB_PID)