platforms/rpi: Clean away the removed hrt_elapsed_time_atomic

Signed-off-by: Jukka Laitinen <jukkax@ssrc.tii.ae>

platforms/nuttx/src/px4/rpi/rpi_common/hrt/hrt.c

@@ -497,20 +497,6 @@ hrt_abstime hrt_absolute_time(void)
 	return ((uint64_t) hi << 32) | lo;
 }
 
-/**
- * Compare a time value with the current time as atomic operation
- */
-hrt_abstime hrt_elapsed_time_atomic(const volatile hrt_abstime *then)
-{
-	irqstate_t flags = px4_enter_critical_section();
-
-	hrt_abstime delta = hrt_absolute_time() - *then;
-
-	px4_leave_critical_section(flags);
-
-	return delta;
-}
-
 /**
  * Store the absolute time in an interrupt-safe fashion
  */