vmount: add param to use RC input for angular rate

Until now RC input was translated to angles only. I added the param
MNT_RC_IN_MODE which allows the RC input to be used for angular rate.

src/modules/vmount/vmount_params.c

@@ -261,3 +261,14 @@ PARAM_DEFINE_FLOAT(MNT_RATE_PITCH, 30.0f);
  * @group Mount
  */
 PARAM_DEFINE_FLOAT(MNT_RATE_YAW, 30.0f);
+
+/**
+ * Input mode for RC gimbal input
+ *
+ * @value 0 Angle
+ * @value 1 Angular rate
+ * @min 0
+ * @max 1
+ * @group Mount
+ */
+PARAM_DEFINE_INT32(MNT_RC_IN_MODE, 1);