Autotest: Update RPM param.

Tools/autotest/common.py

@@ -9856,7 +9856,7 @@ switch value'''
 
     def test_frsky_passthrough(self):
         self.set_parameter("SERIAL5_PROTOCOL", 10) # serial5 is FRSky passthrough
-        self.set_parameter("RPM_TYPE", 10) # enable RPM output
+        self.set_parameter("RPM1_TYPE", 10) # enable RPM output
         self.customise_SITL_commandline([
             "--uartF=tcp:6735" # serial5 spews to localhost:6735
         ])
@@ -10359,7 +10359,7 @@ switch value'''
 
     def test_frsky_sport(self):
         self.set_parameter("SERIAL5_PROTOCOL", 4) # serial5 is FRSky sport
-        self.set_parameter("RPM_TYPE", 10) # enable SITL RPM sensor
+        self.set_parameter("RPM1_TYPE", 10) # enable SITL RPM sensor
         self.customise_SITL_commandline([
             "--uartF=tcp:6735" # serial5 spews to localhost:6735
         ])