Fix order of operands for crc8_l4r

The order in which operands appear in the encoded instruction is different
to order in which they appear in assembly. This changes the XCore backend to
use the instruction encoding order.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173493 91177308-0d34-0410-b5e6-96231b3b80d8