Remove the "fast" form of the list-burr scheduler, and use the

Remove the "fast" form of the list-burr scheduler, and use the
dedicated "fast" scheduler in -fast mode instead, which is
faster. This speeds up llc -fast by a few percent on some
testcases -- the speedup only happens for code not handled by
fast-isel.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59700 91177308-0d34-0410-b5e6-96231b3b80d8