clang-tidy: enable readability-delete-null-pointer and fix

src/modules/airspeed_selector/airspeed_selector_main.cpp

@@ -182,9 +182,7 @@ AirspeedModule::~AirspeedModule()
 
 	perf_free(_perf_elapsed);
 
-	if (_airspeed_validator != nullptr) {
-		delete[] _airspeed_validator;
-	}
+	delete[] _airspeed_validator;
 }
 
 int

src/modules/events/send_event.cpp

@@ -81,13 +81,8 @@ SendEvent::SendEvent() : ModuleParams(nullptr)
 
 SendEvent::~SendEvent()
 {
-	if (_status_display != nullptr) {
-		delete _status_display;
-	}
-
-	if (_rc_loss_alarm != nullptr) {
-		delete _rc_loss_alarm;
-	}
+	delete _status_display;
+	delete _rc_loss_alarm;
 }
 
 int SendEvent::start()

src/modules/mavlink/mavlink_ftp.cpp

@@ -57,13 +57,8 @@ MavlinkFTP::MavlinkFTP(Mavlink *mavlink) :
 
 MavlinkFTP::~MavlinkFTP()
 {
-	if (_work_buffer1) {
-		delete[] _work_buffer1;
-	}
-
-	if (_work_buffer2) {
-		delete[] _work_buffer2;
-	}
+	delete[] _work_buffer1;
+	delete[] _work_buffer2;
 }
 
 unsigned

src/modules/mc_pos_control/mc_pos_control_main.cpp

@@ -297,9 +297,7 @@ MulticopterPositionControl::MulticopterPositionControl() :
 
 MulticopterPositionControl::~MulticopterPositionControl()
 {
-	if (_wv_controller != nullptr) {
-		delete _wv_controller;
-	}
+	delete _wv_controller;
 
 	perf_free(_cycle_perf);
 }

src/modules/uORB/uORBDeviceNode.cpp

@@ -66,9 +66,7 @@ uORB::DeviceNode::DeviceNode(const struct orb_metadata *meta, const uint8_t inst
 
 uORB::DeviceNode::~DeviceNode()
 {
-	if (_data != nullptr) {
-		delete[] _data;
-	}
+	delete[] _data;
 
 	CDev::unregister_driver_and_memory();
 }