Use 'loop rate' term instead of misleading 'loop frequency'

flix/flix.ino

@@ -25,7 +25,7 @@
 
 float t = NAN; // current step time, s
 float dt; // time delta from previous step, s
-float loopFreq; // loop frequency, Hz
+float loopRate; // loop rate, Hz
 int16_t channels[RC_CHANNELS]; // raw rc channels
 float controls[RC_CHANNELS]; // normalized controls in range [-1..1] ([0..1] for throttle)
 float controlsTime; // time of the last controls update