commander: preflight power check ignore module count if USB connected

- this check isn't relevent during bench testing

src/modules/commander/Arming/PreFlightCheck/checks/powerCheck.cpp

@@ -90,10 +90,11 @@ bool PreFlightCheck::powerCheck(orb_advert_t *mavlink_log_pub, const vehicle_sta
 					mavlink_log_critical(mavlink_log_pub, "CAUTION: Avionics Power high: %6.2f Volt", (double)avionics_power_rail_voltage);
 				}
 			}
-		}
 
-		int power_module_count = countSetBits(system_power.brick_valid);
+
-		int required_power_module_count;
+			const int power_module_count = countSetBits(system_power.brick_valid);
+
+			int32_t required_power_module_count = 0;
 			param_get(param_find("COM_POWER_COUNT"), &required_power_module_count);
 
 			if (power_module_count < required_power_module_count) {
@@ -105,6 +106,8 @@ bool PreFlightCheck::powerCheck(orb_advert_t *mavlink_log_pub, const vehicle_sta
 				}
 			}
 
+		}
+
 	} else {
 		if (report_fail) {
 			mavlink_log_critical(mavlink_log_pub, "system power unavailable");