[llvm] [AArch64] update "rm" inline asm test (PR #67472)

[Matthias Braun via llvm-commits]

https://github.com/MatzeB approved this pull request.

The problem here is that it need to be `ldr x0, [x0]` to be valid? Either way removing that constraint makes sense as the `CHECK` line clearly tests for the store necessary for a memory operand. LGTM

https://github.com/llvm/llvm-project/pull/67472