AP_NavEKF3: fixed use of old irqsave() API

libraries/AP_NavEKF3/AP_NavEKF3_core.cpp

@@ -577,7 +577,7 @@ void NavEKF3_core::UpdateFilter(bool predict)
 
     // start the timer used for load measurement
 #if EK3_DISABLE_INTERRUPTS
-    irqstate_t istate = irqsave();
+    void *istate = hal.scheduler->disable_interrupts_save();
 #endif
     hal.util->perf_begin(_perf_UpdateFilter);
 
@@ -628,7 +628,7 @@ void NavEKF3_core::UpdateFilter(bool predict)
     // stop the timer used for load measurement
     hal.util->perf_end(_perf_UpdateFilter);
 #if EK3_DISABLE_INTERRUPTS
-    irqrestore(istate);
+    hal.scheduler->restore_interrupts(istate);
 #endif
 }