delete obsolete and wrong code

"i" runs from 0 to 4 but "add_homeing" array size is 3 only. On the
other hand the calculated value gets overwritten by either one of the
if choice.

Marlin/Marlin.pde

@@ -687,7 +687,6 @@ void process_commands()
         st_synchronize();
       for(int8_t i=0; i < NUM_AXIS; i++) {
         if(code_seen(axis_codes[i])) { 
-           current_position[i] = code_value()+add_homeing[i];  
            if(i == E_AXIS) {
              current_position[i] = code_value();  
              plan_set_e_position(current_position[E_AXIS]);