[PATCH][ARM64] Handle fp128 for parameter passing on stack

[Tim Northover]

Hi Jiangning,

> Attached small patch is to fix an issue around fp128 parameter passing on
> stack.

It'd be nice to make sure the argument ends up where we think it
should in the test (say by returning it and checking for loads from
[sp]).

Other than that, it looks fine. I'll leave it to your discretion
whether to add that modification.

Cheers.

Tim.