AHRS: changed default RP and YAW gain to 0.3

this reduces the impact of hard acceleration on takeoff, and reduces
the impact of GPS lag

Note that this doesn't affect copters, as they override to 0.1

libraries/AP_AHRS/AP_AHRS.cpp

@@ -32,14 +32,14 @@ const AP_Param::GroupInfo AP_AHRS::var_info[] PROGMEM = {
     // @Description: This controls the weight the compass or GPS has on the heading. A higher value means the heading will track the yaw source (GPS or compass) more rapidly.
     // @Range: 0.1 0.4
     // @Increment: .01
-    AP_GROUPINFO("YAW_P", 4,    AP_AHRS, _kp_yaw, 0.4f),
+    AP_GROUPINFO("YAW_P", 4,    AP_AHRS, _kp_yaw, 0.3f),
 
     // @Param: RP_P
     // @DisplayName: AHRS RP_P
     // @Description: This controls how fast the accelerometers correct the attitude
     // @Range: 0.1 0.4
     // @Increment: .01
-    AP_GROUPINFO("RP_P",  5,    AP_AHRS, _kp, 0.4f),
+    AP_GROUPINFO("RP_P",  5,    AP_AHRS, _kp, 0.3f),
 
     // @Param: WIND_MAX
     // @DisplayName: Maximum wind