[clang] [llvm] [AArch64][llvm][clang] Remove `int_aarch64_sve_bfmmla` and reuse existing def (NFC) (PR #193970)

[David Green via cfe-commits]

https://github.com/davemgreen commented:

Hi. Drive by comment - if we are removing the old intrinsic that has been around for a while it is best to add AutoUpgrade code. It is usually pretty simple if it's mostly a  rename.

https://github.com/llvm/llvm-project/pull/193970