Fixup PPC440 load/store operand latencies

The operand latencies for loads and stores in the PPC440 itinerary were wrong
(the store operands are all inputs, and the "with update" (pre-increment)
instructions need a latency for the additional output).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195948 91177308-0d34-0410-b5e6-96231b3b80d8