ARM: remove unused patterns.

There is no sane way for an LEApcrel (= single ADR) instruction to generate a
global address on any ARM target I know of. Fortunately, no-one was trying to
any more, but there were vestigial patterns.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195644 91177308-0d34-0410-b5e6-96231b3b80d8