[clang] [llvm] [AArch64] Remove Automatic Enablement of FEAT_F32MM (PR #85203)

[Jonathan Thackray via llvm-commits]

jthackray wrote:

> When `+sve` is passed in the command line, if the Architecture being targeted is V8.6A/V9.1A or later, `+f32mm` is also added. This enables FEAT_32MM, however at the time of writing no CPU's support this. This leads to the FEAT_32MM instructions being compiled for CPU's that do not support them.
> 
> This commit removes the automatic enablement, however the option is still able to be used by passing `+f32mm`.

Tiny minuscule nit: should be "CPUs" not "CPU's".

https://github.com/llvm/llvm-project/pull/85203