RFR(M): 8213528: fp registers should not need to be saved around a CallLeafNoFP

[Roland Westrelin]

> The we don't need CallLeafNoFPNode, IdealKit::make_leaf_call_no_fp() and NO_FP value. Nobody use it 
> after your change. Or I am missing something?

Indeed there's no more use of IdealKit::make_leaf_call_no_fp() and NO_FP
after my change. I left both there because I suppose some existing calls
to CallLeaf could be turned into the "new" CallLeafNoFP and so this code
might be needed in the future but I can remove it if you like.

Roland.