Define macro HZ_TO_INTERVAL_US() and remove unneeded comments

src/main/common/maths.h

@@ -57,6 +57,8 @@
 
 #define Q12 (1 << 12)
 
+#define HZ_TO_INTERVAL_US(x) (1000000 / (x))
+
 typedef int32_t fix12_t;
 
 typedef struct stdev_s

src/main/sensors/current.c

@@ -140,7 +140,7 @@ currentMeterADCState_t currentMeterADCState;
 void currentMeterADCInit(void)
 {
     memset(&currentMeterADCState, 0, sizeof(currentMeterADCState_t));
-    biquadFilterInitLPF(&adciBatFilter, IBAT_LPF_FREQ, 20000); //50HZ Update
+    biquadFilterInitLPF(&adciBatFilter, IBAT_LPF_FREQ, HZ_TO_INTERVAL_US(50));
 }
 
 void currentMeterADCRefresh(int32_t lastUpdateAt)

src/main/sensors/voltage.c

@@ -191,7 +191,7 @@ void voltageMeterADCInit(void)
         voltageMeterADCState_t *state = &voltageMeterADCStates[i];
         memset(state, 0, sizeof(voltageMeterADCState_t));
 
-        biquadFilterInitLPF(&state->filter, VBAT_LPF_FREQ, 20000); //50HZ Update
+        biquadFilterInitLPF(&state->filter, VBAT_LPF_FREQ, HZ_TO_INTERVAL_US(50));
     }
 }
 
@@ -215,7 +215,7 @@ void voltageMeterESCInit(void)
 {
 #ifdef USE_ESC_SENSOR
     memset(&voltageMeterESCState, 0, sizeof(voltageMeterESCState_t));
-    biquadFilterInitLPF(&voltageMeterESCState.filter, VBAT_LPF_FREQ, 20000); //50HZ Update
+    biquadFilterInitLPF(&voltageMeterESCState.filter, VBAT_LPF_FREQ, HZ_TO_INTERVAL_US(50));
 #endif
 }