Merge pull request #2002 from LMESTM/dev_discof429zi_spipins

[STM32] Add SPI defaults pins to DISCO_F429ZI

Author: sg-

hal/targets/hal/TARGET_STM/TARGET_STM32F4/TARGET_DISCO_F429ZI/PinNames.h

@@ -212,6 +212,11 @@ typedef enum {
     SERIAL_RX   = PA_10,
     USBTX       = PA_9,
     USBRX       = PA_10,
+    SPI_MOSI    = PA_7,
+    SPI_MISO    = PA_6,
+    SPI_SCK     = PA_5,
+    SPI_CS      = PB_6,
+
     // Not connected
     NC = (int)0xFFFFFFFF
 } PinName;