Rely on the code in MatchAddress to do this work. Otherwise we fail to

Rely on the code in MatchAddress to do this work.  Otherwise we fail to
match (X+Y)+(Z << 1), because we match the X+Y first, consuming the index
register, then there is no place to put the Z.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19652 91177308-0d34-0410-b5e6-96231b3b80d8