[MC] Moved all the remaining logic that computed instruction latency and reciprocal...

[MC] Moved all the remaining logic that computed instruction latency and reciprocal throughput from TargetSchedModel to MCSchedModel.

TargetSchedModel now always delegates to MCSchedModel the computation of
instruction latency and reciprocal throughput.
No functional change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330099 91177308-0d34-0410-b5e6-96231b3b80d8