Fixes #1927: THt persistent timer running after model load (with Throttle at -100%)

radio/src/opentx.cpp

@@ -1811,7 +1811,10 @@ void doMixerCalculations()
             timerState->cnt=0;
           }
           else if (tm == TMRMODE_THR_TRG) {
-            if (val || newTimerVal > 0) {
+            if (val) {
+              timerState->state = TMR_TRIGGED;
+            }
+            if (timerState->state == TMR_TRIGGED) {
               newTimerVal++;
             }
           }

radio/src/opentx.h

@@ -860,6 +860,7 @@ extern uint8_t trimsDisplayMask;
 #define TMR_RUNNING  1
 #define TMR_NEGATIVE 2
 #define TMR_STOPPED  3
+#define TMR_TRIGGED  4
 void timerReset(uint8_t idx);
 void flightReset();