[llvm] [Utils] update_llc_test_checks.py: updated the regexp for ARM target (PR #148287)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

@jrtc27 please can you review - I think #139844 introduced the regression - should the other arm/thumb regexp be updated similarly?

https://github.com/llvm/llvm-project/pull/148287