[TableGen] Remove unnecessary map lookup and shadowing of a variable. NFCI

We already have an OldSCIdx variable in the outer loop here. And we already did the map lookup in the loop that populated ClassInstrs. And the outer OldSCIdx got it from ClassInstrs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@328139 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed