VOXL2: HRT updates for synchronization with Qurt time (#22881)

- Added offset to Posix hrt time to account for synchronization with Qurt hrt time
- Added new Kconfig to configure synchronization of HRT timestamps on VOXL2
- Moved voxl2 libfc sensor library submodule from muorb module to boards directory
- Added check to make sure hrt_elapsed_time can never be negative

platforms/posix/src/px4/common/drv_hrt.cpp

@@ -51,6 +51,11 @@
 #include <errno.h>
 #include "hrt_work.h"
 
+// Voxl2 board specific API definitions to get time offset
+#if defined(CONFIG_MUORB_APPS_SYNC_TIMESTAMP)
+#include "fc_sensor.h"
+#endif
+
 #if defined(ENABLE_LOCKSTEP_SCHEDULER)
 #include <lockstep_scheduler/lockstep_scheduler.h>
 static LockstepScheduler lockstep_scheduler {true};
@@ -107,6 +112,29 @@ hrt_abstime hrt_absolute_time()
 #else // defined(ENABLE_LOCKSTEP_SCHEDULER)
 	struct timespec ts;
 	px4_clock_gettime(CLOCK_MONOTONIC, &ts);
+
+# if defined(CONFIG_MUORB_APPS_SYNC_TIMESTAMP)
+	hrt_abstime temp_abstime = ts_to_abstime(&ts);
+	int apps_time_offset = fc_sensor_get_time_offset();
+
+	if (apps_time_offset < 0) {
+		hrt_abstime temp_offset = -apps_time_offset;
+
+		if (temp_offset >= temp_abstime) {
+			temp_abstime = 0;
+
+		} else {
+			temp_abstime -= temp_offset;
+		}
+
+	} else {
+		temp_abstime += (hrt_abstime) apps_time_offset;
+	}
+
+	ts.tv_sec = temp_abstime / 1000000;
+	ts.tv_nsec = (temp_abstime % 1000000) * 1000;
+# endif // defined(CONFIG_MUORB_APPS_SYNC_TIMESTAMP)
+
 	return ts_to_abstime(&ts);
 #endif // defined(ENABLE_LOCKSTEP_SCHEDULER)
 }
@@ -449,6 +477,7 @@ int px4_clock_gettime(clockid_t clk_id, struct timespec *tp)
 
 #endif // defined(ENABLE_LOCKSTEP_SCHEDULER)
 	return system_clock_gettime(clk_id, tp);
+
 }
 
 #if defined(ENABLE_LOCKSTEP_SCHEDULER)