ARM: remove @llvm.arm.sevl

This intrinsic is no longer needed with the new @llvm.arm.hint(i32) intrinsic
which provides a generic, extensible manner for adding hint instructions.  This
functionality can now be represented as @llvm.arm.hint(i32 5).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207246 91177308-0d34-0410-b5e6-96231b3b80d8