R600: Rename 128 bit registers.

R600: Rename 128 bit registers.

Almost all instructions that takes a 128 bits reg as input (fetch, export...)
have the abilities to swizzle their argument and output. Instead of printing
default swizzle for each 128 bits reg, rename T*.XYZW to T* and let instructions
print potentially optimized swizzles themselves.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182124 91177308-0d34-0410-b5e6-96231b3b80d8