ARMClang: Remove orphaned linker --list option

Setting the `armlink --list` option without other diagnostic flags is
misleading because it produces an empty file and prevents the user from
printing diagnostics to the standard output or redirecting them to
another file.

It's unclear why the flag was added when support for ARMClang was first
added by commit 7b0abaac31 (ARMClang: Add support for Clang-based ARM
compiler, 2019-05-13, v3.15.0-rc1~111^2).

Fixes: #21538