[TableGen] Simplify some code slightly. No need to check if the arrays are empty...

[TableGen] Simplify some code slightly. No need to check if the arrays are empty before printing. The loop can be made to print the same thing if the loop is empty. NFC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256703 91177308-0d34-0410-b5e6-96231b3b80d8