AP_ExternalAHRS: added vnav linux target

libraries/AP_ExternalAHRS/AP_ExternalAHRS.cpp

@@ -100,6 +100,11 @@ AP_ExternalAHRS::AP_ExternalAHRS()
     _singleton = this;
 }
 
+#ifndef HAL_EXTERNAL_AHRS_DEFAULT
+#define HAL_EXTERNAL_AHRS_DEFAULT 0
+#endif
+
+
 // table of user settable parameters
 const AP_Param::GroupInfo AP_ExternalAHRS::var_info[] = {
 
@@ -108,7 +113,7 @@ const AP_Param::GroupInfo AP_ExternalAHRS::var_info[] = {
     // @Description: Type of AHRS device
     // @Values: 0:None,1:VectorNav
     // @User: Standard
-    AP_GROUPINFO_FLAGS("_TYPE", 1, AP_ExternalAHRS, devtype, float(DevType::None), AP_PARAM_FLAG_ENABLE),
+    AP_GROUPINFO_FLAGS("_TYPE", 1, AP_ExternalAHRS, devtype, HAL_EXTERNAL_AHRS_DEFAULT, AP_PARAM_FLAG_ENABLE),
 
     AP_GROUPEND
 };