ERROR macro: get rid of the many 'oddly, ERROR is not defined for c++', use PX4_ERROR

src/drivers/airspeed/airspeed.cpp

@@ -124,7 +124,7 @@ Airspeed::~Airspeed()
 int
 Airspeed::init()
 {
-	int ret = ERROR;
+	int ret = PX4_ERROR;
 
 	/* do I2C init (and probe) first */
 	if (I2C::init() != OK) {

src/drivers/airspeed/airspeed.h

@@ -39,6 +39,7 @@
  */
 
 #include <px4_config.h>
+#include <px4_defines.h>
 
 #include <drivers/device/i2c.h>
 
@@ -82,12 +83,6 @@
 /* Default I2C bus */
 #define PX4_I2C_BUS_DEFAULT		PX4_I2C_BUS_EXPANSION
 
-/* Oddly, ERROR is not defined for C++ */
-#ifdef ERROR
-# undef ERROR
-#endif
-static const int ERROR = -1;
-
 #ifndef CONFIG_SCHED_WORKQUEUE
 # error This requires CONFIG_SCHED_WORKQUEUE.
 #endif