[llvm] [AArch64] Allow single-element vector FP converts with +fprcvt (PR #169692)

[Amina Chabane via llvm-commits]

Amichaxx wrote:

This patch was initially intended to be a follow-up patch to #112905, but has since been extended to included the further suggested patterns in this patch as well.

https://github.com/llvm/llvm-project/pull/169692