* Add support for encoding t_addrmode_s2 and t_addrmode_s1. They are the same as

  t_addrmode_s4, but with a different scaling factor.

* Encode the Thumb1 load and store instructions. This involved a bit of
  refactoring (hi, Chris! :-). Some of the patterns became dead afterwards and
  were removed.

llvm-svn: 120482