Revert "[AArch64] Add DAG combine for extract extend pattern"

This reverts commit r255895. The patch breaks internal tests. Reverting until a
fix is ready.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255928 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed