Add OpSize16 flags to 32-bit CRC32 instructions so they can be encoded correctly in 16-bit mode.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199478 91177308-0d34-0410-b5e6-96231b3b80d8
Switch a few instructions to use RI instead I so they don't require REX_W to be explicitly specified.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199479 91177308-0d34-0410-b5e6-96231b3b80d8