Add missing definitions for MISO etc to F4 core

Author: rogerclarkmelbourne

STM32F4/variants/discovery_f407/variant.h

@@ -11,4 +11,10 @@
 
 #define portConfigRegister(pin)		( &(PIN_MAP[pin].gpio_device->regs->CRL) )
 
+static const uint8_t SS   = BOARD_SPI1_NSS_PIN;
+static const uint8_t SS1  = BOARD_SPI2_NSS_PIN;
+static const uint8_t MOSI = BOARD_SPI1_MOSI_PIN;
+static const uint8_t MISO = BOARD_SPI1_MISO_PIN;
+static const uint8_t SCK  = BOARD_SPI1_SCK_PIN;
+
 #endif /* _VARIANT_ARDUINO_STM32_ */