Disable LPE in px4fmu-v2_default

With GCC 4.9 the binary is to large for the flash memory.
This is why we disabled LPE on that platform.

ROMFS/px4fmu_common/init.d/rc.mc_apps

@@ -19,8 +19,14 @@ fi
 # LPE
 if param compare SYS_MC_EST_GROUP 1
 then
-	attitude_estimator_q start
-	local_position_estimator start
+	# Try to start LPE. If it fails, start EKF2 as a default
+	# Unfortunately we do not build it on px4fmu-v2 duo to a limited flash.
+	if attitude_estimator_q start
+	then
+		local_position_estimator start
+	else
+		ekf2 start
+	fi
 fi
 
 # EKF

ROMFS/px4fmu_common/init.d/rc.vtol_apps

@@ -20,8 +20,14 @@ fi
 # LPE
 if param compare SYS_MC_EST_GROUP 1
 then
-	attitude_estimator_q start
-	local_position_estimator start
+	# Try to start LPE. If it fails, start EKF2 as a default
+	# Unfortunately we do not build it on px4fmu-v2 duo to a limited flash.
+	if attitude_estimator_q start
+	then
+		local_position_estimator start
+	else
+		ekf2 start
+	fi
 fi
 
 # EKF

cmake/configs/nuttx_px4fmu-v2_default.cmake

@@ -96,9 +96,9 @@ set(config_module_list
 	#
 	# Estimation modules
 	#
-	modules/attitude_estimator_q
+	#modules/attitude_estimator_q
 	#modules/position_estimator_inav
-	modules/local_position_estimator
+	#modules/local_position_estimator
 	modules/ekf2
 
 	#