util: Delete the aarch64 Makefile for the m5 utility.
util: Delete the aarch64 Makefile for the m5 utility.

Change-Id: I202f2b0986ef12ddb076045673d80405b1afb54a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/27215
Reviewed-by: Giacomo Travaglini <8eef13a4f970e2e9372c8d26ad0737b760f99c02@arm.com>
Reviewed-by: Daniel Carvalho <91779fc734d358d9575ec4910de29bfcbcaf1b22@yahoo.com.br>
Maintainer: Giacomo Travaglini <8eef13a4f970e2e9372c8d26ad0737b760f99c02@arm.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5