R600/SI: Cleanup parsing of register names.

Try to figure out the class and number of subregisters.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206334 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Print more immediates in hex format

Print in decimal for inline immediates, and hex otherwise. Use hex
always for offsets in addressing offsets.

This approximately matches what the shader compiler does.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206335 91177308-0d34-0410-b5e6-96231b3b80d8