[Hexagon] Remove incorrect pattern for swiz

[Hexagon] Remove incorrect pattern for swiz

The pattern had a couple of problems:
- It was checking for loads of bytes in the reverse order to what it
  should have been looking for.
- It would replace loads of bytes with a load of a word without making
  sure that the alignment was correct.

Thanks to Eli Friedman for pointing it out.

llvm-svn: 343514