[llvm] [RISC-V][MC] Reject x0 as the temporary register for store pseudos (PR #227512)

[Sam Elliott via llvm-commits]

lenary wrote:

Broadly in favour, but we need to apply it to the float loads (which have a temporary like the stores do), and the normal loads (which would access the wrong address if used with `x0`).

I'll have a think what to do about the xqci pseudos, but they also likely need to follow this too.

https://github.com/llvm/llvm-project/pull/227512