stm32/boards/ARDUINO_PORTENTA_H7: Add pin configuration for SPI1.

Currently, only the processor's SPI2 bus is enabled (though the related
pins are labeled SPI1 in the Portenta H7 documentation).  This commit
enables the processor's SPI1 bus, which is accessible via the board's
high-density connectors.

Signed-off-by: Jim Lipsey <github@lipsey.org>

ports/stm32/boards/ARDUINO_PORTENTA_H7/mpconfigboard.h

@@ -170,7 +170,12 @@ extern struct _spi_bdev_t spi_bdev;
 #define MICROPY_HW_I2C3_SCL         (pin_H7)
 #define MICROPY_HW_I2C3_SDA         (pin_H8)
 
-// SPI
+// SPI buses
+#define MICROPY_HW_SPI1_NSS         (pin_C13)
+#define MICROPY_HW_SPI1_SCK         (pin_B3)
+#define MICROPY_HW_SPI1_MISO        (pin_B4)
+#define MICROPY_HW_SPI1_MOSI        (pin_D7)
+
 #define MICROPY_HW_SPI2_NSS         (pin_I0)
 #define MICROPY_HW_SPI2_SCK         (pin_I1)
 #define MICROPY_HW_SPI2_MISO        (pin_C2)