NV14: fixed PPM/heartbeat pin polarity

Now it should now correspond to the exact same config as the other radios have hard-wired.

radio/src/targets/nv14/extmodule_helper.cpp

@@ -59,6 +59,6 @@ void extModuleInit()
   GPIO_InitStructure.GPIO_Pin = EXTMODULE_RX_INVERT_GPIO_PIN;
   GPIO_Init(EXTMODULE_RX_INVERT_GPIO, &GPIO_InitStructure);
 
-  GPIO_ResetBits(EXTMODULE_TX_INVERT_GPIO, EXTMODULE_TX_INVERT_GPIO_PIN);
-  GPIO_ResetBits(EXTMODULE_RX_INVERT_GPIO, EXTMODULE_RX_INVERT_GPIO_PIN);
+  EXTMODULE_TX_INVERTED();
+  EXTMODULE_RX_INVERTED();
 }