APM_RC_APM1.cpp: Bugfix on mapping of SetFastOutputChannels to ICR reg

* Previously had the ICR register for ch1/2/9 (on timer5) swapped with
  ch3/4/10 (on timer1).
* This bug probably didn't make a difference in operation since
  SetFastOutputChannels is typically only used for copters, where at
  least CH1,2,3,4 would be set to fast all at once.

libraries/APM_RC/APM_RC_APM1.cpp

@@ -271,11 +271,11 @@ void APM_RC_APM1::SetFastOutputChannels(uint32_t chmask, uint16_t speed_hz)
     uint16_t icr = _map_speed(speed_hz);
 
     if ((chmask & ( _BV(CH_1) | _BV(CH_2) | _BV(CH_9))) != 0) {
-        ICR1 = icr;
+        ICR5 = icr;
     }
 
     if ((chmask & ( _BV(CH_3) | _BV(CH_4) | _BV(CH_10))) != 0) {
-        ICR5 = icr;
+        ICR1 = icr;
     }
 
  #if 0