AP_HAL_Linux: remove unused constant

libraries/AP_HAL_Linux/SPIDriver.cpp

@@ -161,7 +161,7 @@ void SPIDeviceManager::init()
         }
         char path[255];
         snprintf(path, sizeof(path), "/dev/spidev%u.%u",
-                 _device[i]._bus + LINUX_SPIDEV_BUS_OFFSET, _device[i]._subdev);
+                 _device[i]._bus, _device[i]._subdev);
         _device[i]._fd = open(path, O_RDWR);
         if (_device[i]._fd == -1) {
             printf("Unable to open %s - %s\n", path, strerror(errno));

libraries/AP_HAL_Linux/SPIDriver.h

@@ -5,11 +5,6 @@
 #include "AP_HAL_Linux.h"
 #include "Semaphores.h"
 
-// Most platforms won't need to declare the spidev bus offset
-#ifndef LINUX_SPIDEV_BUS_OFFSET
-#define LINUX_SPIDEV_BUS_OFFSET 0
-#endif
-
 #define LINUX_SPI_MAX_BUSES 3
 
 // Fake CS pin to indicate in-kernel handling