[X86][Broadwell] HWPort5 should not be added to BroadwellModelProcResources.

The BroadwellModelProcResources had an entry for HWPort5, which is a Haswell
resource, and not a Broadwell processor resource. That entry was added to the
Broadwell model because variable blends were consuming it.

This was clearly a typo (the resource name should have been BWPort5), which
unfortunately was never caught before. It was not reported as an error because
HWPort5 is a resource defined by the Haswell model. It has been found when
testing some code with llvm-mca: the list of resources in the resource pressure
view was odd.

This patch fixes the issue; now variable blend instructions consume 2 cycles on
BWPort5 instead of HWPort5. This is enough to get rid of the extra (spurious)
entry in the BroadWellModelProcResources table.

llvm-svn: 329686