Revert change to src/drivers/device/vdev.cpp

This change was not part of the orb_advert_t fix.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

src/drivers/airspeed/airspeed.cpp

@@ -367,7 +367,7 @@ Airspeed::update_status()
 			SUBSYSTEM_TYPE_DIFFPRESSURE
 		};
 
-		if (_subsys_pub == nullptr) {
+		if (_subsys_pub != nullptr) {
 			orb_publish(ORB_ID(subsystem_info), _subsys_pub, &info);
 		} else {
 			_subsys_pub = orb_advertise(ORB_ID(subsystem_info), &info);

src/drivers/device/vdev.cpp

@@ -64,7 +64,7 @@ private:
 	px4_dev_t() {}
 };
 
-#define PX4_MAX_DEV 100
+#define PX4_MAX_DEV 50
 static px4_dev_t *devmap[PX4_MAX_DEV];
 
 /*