AP_HAL_Linux: RCOutput_Sysfs: fix deleting _pwm_channels array

delete [] should be called rather than delete.

libraries/AP_HAL_Linux/RCOutput_Sysfs.cpp

@@ -37,7 +37,7 @@ RCOutput_Sysfs::~RCOutput_Sysfs()
         delete _pwm_channels[i];
     }
 
-    delete _pwm_channels;
+    delete [] _pwm_channels;
 }
 
 void RCOutput_Sysfs::init()