MIRTests: Remove unnecessary 2>&1 redirection

llc mir output goes to stdout nowadays, so the 2>&1 is not necessary
anymore for most tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295859 91177308-0d34-0410-b5e6-96231b3b80d8
69 files changed