[X86][Broadwell] Added the broadwell cpu to the scheduling regression tests.<NFC>

[X86][Broadwell] Added the broadwell cpu to the scheduling regression tests.<NFC>

NFC.
Added the Broadwell cpu and the BROADWELL prefix to all the scheduling regression tests, as part of prepartion for a larger commit of adding all Broadwell scheduiling.

Reviewers: RKSimon, zvi, aaboud
Differential Revision: https://reviews.llvm.org/D38994

Change-Id: I54bc9065168844c107b1729fcdc1d311ce3ea0a9

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315998 91177308-0d34-0410-b5e6-96231b3b80d8