Add API to grab handle of platform SPI device (#3029)

***NO_CI***

Author: josesimoes

src/PAL/Include/CPU_SPI_decl.h

@@ -169,4 +169,7 @@ uint32_t CPU_SPI_ChipSelectLineCount(uint32_t busIndex);
 HRESULT CPU_SPI_MinClockFrequency(uint32_t busIndex, int32_t *frequency);
 HRESULT CPU_SPI_MaxClockFrequency(uint32_t busIndex, int32_t *frequency);
 
+// return the SPI hande for the SPI device (platform specific)
+uint32_t CPU_SPI_GetSpiHandle(uint32_t deviceHandle);
+
 #endif // DRIVERS_SPI_DECL_H

src/System.Device.Spi/nanoHAL_Spi.cpp

@@ -481,3 +481,19 @@ HRESULT nanoSPI_Write_Read(
         readPtr,
         readSize);
 }
+
+//
+// Get the SPI handle from the device handle
+//
+uint32_t CPU_SPI_GetSpiHandle(uint32_t deviceHandle)
+{
+    uint8_t spiBus;
+    int deviceIndex;
+
+    if (!getDevice(deviceHandle, spiBus, deviceIndex))
+    {
+        return 0;
+    }
+
+    return spiconfig[spiBus].deviceHandles[deviceIndex];
+}