fix unit-tests

Author: jcohen-apple

llvm/test/CodeGen/AArch64/aarch64-combine-split-loads.mir

@@ -1,5 +1,5 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
-# RUN: llc -run-pass=machine-combiner -mcpu=neoverse-n2 -verify-machineinstrs %s -o - | FileCheck %s
+# RUN: llc -run-pass=machine-combiner -mcpu=neoverse-n2 -mtriple=aarch64-none-linux-gnu -verify-machineinstrs %s -o - | FileCheck %s
 
 ---
 name:            split_loads_to_fpr128