[AArch64] Deprecate a command-line option used for testing.

Support for pairing unscaled loads and stores has been enabled since the
original ARM64 port.  This feature is no longer experimental, AFAICT.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249049 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed