[llvm] [AArch64] use `isTRNMask` to calculate shuffle costs (PR #171524)

[Philip Ginsbach-Chen via llvm-commits]

ginsbach wrote:

I think the test failure is unrelated and seems to have been introduced by https://github.com/llvm/llvm-project/pull/167798.

https://github.com/llvm/llvm-project/pull/171524