[RegAlloc] Remove reference to the trivial spiller in test case.

This test case was never actually testing the trivial spiller: the -spiller
option has not been hooked up for a while now.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221475 91177308-0d34-0410-b5e6-96231b3b80d8