Rename struct element for clarity (#2491)

***NO_CI***

Author: josesimoes

src/PAL/Include/CPU_SPI_decl.h

@@ -74,7 +74,7 @@ struct SPI_DEVICE_CONFIGURATION
     // SPI bus Configuration (full-duplex is default)
     SpiBusConfiguration BusConfiguration;
     // True = SPI data takes the form of 16-bit words otherwise 8-bit words.
-    bool MD16bits;
+    bool DataIs16bits;
     // Data order for 16 bit operation
     DataBitOrder DataOrder16;
     // Rough estimate on the time it takes to send/receive one byte (in milliseconds)

src/System.Device.Spi/sys_dev_spi_native_System_Device_Spi_SpiDevice.cpp

@@ -289,6 +289,7 @@ HRESULT Library_sys_dev_spi_native_System_Device_Spi_SpiDevice::NativeOpenDevice
     config = pThis[Library_sys_dev_spi_native_System_Device_Spi_SpiDevice::FIELD___connectionSettings].Dereference();
 
     spiConfig.BusMode = SpiBusMode_master;
+    spiConfig.DataIs16bits = false;
 
     // internally SPI bus ID is zero based, so better take care of that here
     spiConfig.Spi_Bus = config[SpiConnectionSettings::FIELD___busId].NumericByRef().s4 - 1;