[llvm-mca][BtVer2] Modify ANDN tests in zero-idioms-avx-256.s. NFC

Two test cases should have tested 256-bit variants of VANDN zero-idioms instead
of the 128-bit variants.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342655 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed