Add getDataOrderSPI API to Sercom

cores/arduino/SERCOM.cpp

@@ -262,6 +262,11 @@ void SERCOM::setDataOrderSPI(SercomDataOrder dataOrder)
   enableSPI();
 }
 
+SercomDataOrder SERCOM::getDataOrderSPI()
+{
+  return (sercom->SPI.CTRLA.bit.DORD ? LSB_FIRST : MSB_FIRST);
+}
+
 void SERCOM::setBaudrateSPI(uint8_t divider)
 {
   //Can't divide by 0

cores/arduino/SERCOM.h

@@ -173,6 +173,7 @@ class SERCOM
 		void enableSPI( void ) ;
 		void disableSPI( void ) ;
 		void setDataOrderSPI(SercomDataOrder dataOrder) ;
+		SercomDataOrder getDataOrderSPI( void ) ;
 		void setBaudrateSPI(uint8_t divider) ;
 		void setClockModeSPI(SercomSpiClockMode clockMode) ;
 		void writeDataSPI(uint8_t data) ;