AHRS: fix example sketch to use roll/pitch trim

libraries/AP_InertialSensor/examples/MPU6000/MPU6000.pde

@@ -102,6 +102,7 @@ void loop(void)
 
 void run_calibration()
 {
+    float roll_trim, pitch_trim;
     // clear off any other characters (like line feeds,etc)
     while( hal.console->available() ) {
         hal.console->read();
@@ -110,7 +111,7 @@ void run_calibration()
 
 #if !defined( __AVR_ATmega1280__ )
     AP_InertialSensor_UserInteractStream interact(hal.console);
-    ins.calibrate_accel(NULL, &interact);
+    ins.calibrate_accel(NULL, &interact, roll_trim, pitch_trim);
 #else
 	hal.console->println_P(PSTR("calibrate_accel not available on 1280"));
 #endif