AP_HAL_Linux: AnalogIn_IIO: formatting fixes

- remove trailing whitespaces
  - use pragma 0 for header guard

libraries/AP_HAL_Linux/AnalogIn_IIO.cpp

@@ -6,8 +6,6 @@
 
 extern const AP_HAL::HAL& hal;
 
-
-
 const char* IIOAnalogSource::analog_sources[IIO_ANALOG_IN_COUNT] = {
 #if CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_PXF
     "in_voltage0_raw",

libraries/AP_HAL_Linux/AnalogIn_IIO.h

@@ -1,6 +1,4 @@
-
-#ifndef __AP_HAL_IIO_ANALOGIN_H__
-#define __AP_HAL_IIO_ANALOGIN_H__
+#pragma once
 
 #include "AP_HAL_Linux.h"
 #include <AP_ADC/AP_ADC.h>
@@ -61,4 +59,3 @@ public:
     float board_voltage(void) { return 0.0f; }
 
 };
-#endif // __AP_HAL_IIO_ANALOGIN_H__