Change MPC_ACC_HOR_MAX default to 2.0

ROMFS/px4fmu_common/init.d/rc.vtol_defaults

@@ -23,6 +23,7 @@ then
 	param set MPC_Z_VEL_MAX 1.5
 	param set MPC_XY_VEL_MAX 4.0
 	param set MIS_YAW_TMT 10
+	param set MPC_ACC_HOR_MAX 2.0
 fi
 
 set PWM_DISARMED 900