mc_pos_control_params: fix param descriptions for negative values

src/modules/mc_pos_control/mc_pos_control_params.c

@@ -759,7 +759,7 @@ PARAM_DEFINE_INT32(MPC_YAW_MODE, 0);
  *
  * If set to a value greater than zero, other parameters are automatically set (such as
  * the acceleration or jerk limits).
- * If set to -1, the existing individual parameters are used.
+ * If set to a negative value, the existing individual parameters are used.
  *
  * @min -1
  * @max 1
@@ -774,7 +774,7 @@ PARAM_DEFINE_FLOAT(SYS_VEHICLE_RESP, -0.4f);
  *
  * If set to a value greater than zero, other parameters are automatically set (such as
  * MPC_XY_VEL_MAX or MPC_VEL_MANUAL).
- * If set to -1, the existing individual parameters are used.
+ * If set to a negative value, the existing individual parameters are used.
  *
  * @min -20
  * @max 20
@@ -789,7 +789,7 @@ PARAM_DEFINE_FLOAT(MPC_XY_VEL_ALL, -10.0f);
  *
  * If set to a value greater than zero, other parameters are automatically set (such as
  * MPC_Z_VEL_MAX_UP or MPC_LAND_SPEED).
- * If set to -1, the existing individual parameters are used.
+ * If set to a negative value, the existing individual parameters are used.
  *
  * @min -3
  * @max 8