Copter: backoff autotune discovered Stab P to 90%

ArduCopter/control_autotune.pde

@@ -70,7 +70,7 @@
 #define AUTOTUNE_D_UP_DOWN_MARGIN          0.2f     // The margin below the target that we tune D in
 #define AUTOTUNE_RD_BACKOFF                1.0f     // Rate D gains are reduced to 50% of their maximum value discovered during tuning
 #define AUTOTUNE_RP_BACKOFF                1.0f     // Rate P gains are reduced to 97.5% of their maximum value discovered during tuning
-#define AUTOTUNE_SP_BACKOFF                1.0f     // Stab P gains are reduced to 60% of their maximum value discovered during tuning
+#define AUTOTUNE_SP_BACKOFF                0.9f     // Stab P gains are reduced to 90% of their maximum value discovered during tuning
 #define AUTOTUNE_ACCEL_RP_BACKOFF          1.0f     // back off from maximum acceleration
 #define AUTOTUNE_ACCEL_Y_BACKOFF          0.75f     // back off from maximum acceleration