llvm: Allow llvm-readelf

Enable multiple names for the readelf program under llvm

See https://github.com/zephyrproject-rtos/zephyr/pull/66054
Change-Id: I432c493eb2f03a911b2162e86cb868d7b437d7c9
Signed-off-by: Yuval Peress <peress@google.com>
Reviewed-on: https://pigweed-review.googlesource.com/c/third_party/github/zephyrproject-rtos/zephyr/+/183248
Reviewed-by: Rob Mohr <mohrr@google.com>