AP_RangeFinder: remove param conversion for 3rd and 4th

3rd and 4th instances were not available to users unless they used their own builds which is rare
this reduces the firmware's flash size a small amount

libraries/AP_RangeFinder/RangeFinder.cpp

@@ -210,38 +210,6 @@ void RangeFinder::convert_params(void) {
             {24, 11, 1}, //24, ADDR 2
             {50, 12, 1}, //50, POS 2
             {54, 13, 1}, //54, ORIENT 2
-
-            // rangefinder 3
-            {25, 0, 2}, //25, TYPE 3
-            {26, 1, 2}, //26, PIN 3
-            {27, 2, 2}, //27, SCALING 3
-            {28, 3, 2}, //28, OFFSET 3
-            {29, 4, 2}, //29, FUNCTION 3
-            {30, 5, 2}, //30, MIN_CM 3
-            {31, 6, 2}, //31, MAX_CM 3
-            {32, 7, 2}, //32, STOP_PIN 3
-            {34, 8, 2}, //34, RMETRIC 3
-            {10, 9, 2}, //10, PWRRNG 1 (previously existed only once for all sensors)
-            {35, 10, 2}, //35, GNDCLEAR 3
-            {36, 11, 2}, //36, ADDR 3
-            {51, 12, 2}, //51, POS 3
-            {55, 13, 2}, //55, ORIENT 3
-
-            // rangefinder 4
-            {37, 0, 3}, //37, TYPE 4
-            {38, 1, 3}, //38, PIN 4
-            {39, 2, 3}, //39, SCALING 4
-            {40, 3, 3}, //40, OFFSET 4
-            {41, 4, 3}, //41, FUNCTION 4
-            {42, 5, 3}, //42, MIN_CM 4
-            {43, 6, 3}, //43, MAX_CM 4
-            {44, 7, 3}, //44, STOP_PIN 4
-            {46, 8, 3}, //46, RMETRIC 4
-            {10, 9, 3}, //10, PWRRNG 1 (previously existed only once for all sensors)
-            {47, 10, 3}, //47, GNDCLEAR 4
-            {48, 11, 3}, //48, ADDR 4
-            {52, 12, 3}, //52, POS 4
-            {56, 13, 3}, //56, ORIENT 4
     };
 
     char param_name[17] = {0};