mesa: remove redundant _MaxElement computation

Eric added some new code to check if offset < obj_size before computing
_MaxElement but my original code was still present afterward and it
clobbered the _MaxElement value.

Not sure if this came from a bad merge or what.

src/mesa/main/state.c

@@ -82,12 +82,6 @@ compute_max_element(struct gl_client_array *array)
       } else {
 	 array->_MaxElement = 0;
       }
-      /* Compute the max element we can access in the VBO without going
-       * out of bounds.
-       */
-      array->_MaxElement = ((GLsizeiptrARB) array->BufferObj->Size
-                            - (GLsizeiptrARB) array->Ptr + array->StrideB
-                            - array->_ElementSize) / array->StrideB;
    }
    else {
       /* user-space array, no idea how big it is */