ARM: remove special cases for Darwin dynamic-no-pic mode.

These are handled almost identically to static mode (and ELF's global address
materialisation), except that a symbol may have "$non_lazy_ptr" appended. This
can be handled by passing appropriate flags along with the instruction instead
of using entirely separate pseudo-instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195655 91177308-0d34-0410-b5e6-96231b3b80d8