[clang] [CIR][AArch64] Upstream vrshrd_n_s64/u64 and vrshr_n_v vector rounding shift right (PR #185992)

[Md Mouzam Arfi Hussain via cfe-commits]

ArfiH wrote:

> @ArfiH , any luck applying my diff? If you are still struggling, I can complete this PR for you.
> 
> Thank you, -Andrzej

Hi, yes please! I'd really appreciate that.

https://github.com/llvm/llvm-project/pull/185992