[aarch64] set acl_build_flags arch=armv8a, remove editing build flags (#1550)

Looking at this PR:
#1370
this line:
https://github.com/pytorch/builder/pull/1370/files#diff-54480d0a69ca27f54fb0736a9762caa8b03bd4736dcd77190d99ec3033c9bd2fR229

That fixed the issue:
pytorch/pytorch#97226

One of the changes is to set 
```
arch=armv8a
```
We are experiencing the same issue now: pytorch/pytorch#109312
Hence this fix.

Author: atalman

aarch64_linux/aarch64_wheel_ci_build.py

@@ -21,11 +21,8 @@ def build_ArmComputeLibrary(git_clone_flags: str = "") -> None:
     print('Building Arm Compute Library')
     os.system("cd / && mkdir /acl")
     os.system(f"git clone https://github.com/ARM-software/ComputeLibrary.git -b v23.05.1 {git_clone_flags}")
-    os.system('sed -i -e \'s/"armv8.2-a"/"armv8-a"/g\' ComputeLibrary/SConscript; '
-              'sed -i -e \'s/-march=armv8.2-a+fp16/-march=armv8-a/g\' ComputeLibrary/SConstruct; '
-              'sed -i -e \'s/"-march=armv8.2-a"/"-march=armv8-a"/g\' ComputeLibrary/filedefs.json')
     os.system("cd ComputeLibrary; export acl_install_dir=/acl; "
-              "scons Werror=1 -j8 debug=0 neon=1 opencl=0 os=linux openmp=1 cppthreads=0 arch=armv8.2-a multi_isa=1 build=native build_dir=$acl_install_dir/build; "
+              "scons Werror=1 -j8 debug=0 neon=1 opencl=0 os=linux openmp=1 cppthreads=0 arch=armv8a multi_isa=1 build=native build_dir=$acl_install_dir/build; "
               "cp -r arm_compute $acl_install_dir; "
               "cp -r include $acl_install_dir; "
               "cp -r utils $acl_install_dir; "