R600/SI: Fix definitions for ds_read2 / ds_write2 instructions.

These were just wrong, using the wrong register classes
and store2 was missing an operand.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214756 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed