More cleanups for CellSPU:

More cleanups for CellSPU:

- Expand tabs... (poss 80-col violations, will get them later...)
- Consolidate logic for SelectDFormAddr and SelectDForm2Addr into a single
  function, simplifying maintenance. Also reduced custom instruction
  generation for SPUvecinsert/INSERT_MASK.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46544 91177308-0d34-0410-b5e6-96231b3b80d8