C2: Remove no-op checking for callee-saved-floats

In C2Compiler::init_c2_runtime, there is a block:

  // Check that runtime and architecture description agree on callee-saved-floats
  bool callee_saved_floats = false;
  for( OptoReg::Name i=OptoReg::Name(0); i<OptoReg::Name(_last_Mach_Reg); i = OptoReg::add(i,1) ) {
    // Is there a callee-saved float or double?
    if( register_save_policy[i] == 'E' /* callee-saved */ &&
       (register_save_type[i] == Op_RegF || register_save_type[i] == Op_RegD) ) {
      callee_saved_floats = true;
    }
  }

Yet, it does not do anything, because callee_saved_floats is unused.

It seems to be this way since the initial load.