added spi code for linux

linux/spi/spiDefinitions.h

@@ -0,0 +1,17 @@
+#ifndef LINUX_SPI_SPIDEFINITONS_H_
+#define LINUX_SPI_SPIDEFINITONS_H_
+
+#include <cstdint>
+
+namespace spi {
+
+enum SpiModes: uint8_t {
+    MODE_0,
+    MODE_1,
+    MODE_2,
+    MODE_3
+};
+
+}
+
+#endif /* LINUX_SPI_SPIDEFINITONS_H_ */