[fix] Update torch version in cpu-build.txt for AArch64/ppc64le and Darwin (#25579)

Signed-off-by: Fadi Arafeh <fadi.arafeh@arm.com>

requirements/cpu-build.txt

@@ -6,7 +6,8 @@ packaging>=24.2
 setuptools>=77.0.3,<80.0.0
 setuptools-scm>=8
 --extra-index-url https://download.pytorch.org/whl/cpu
-torch==2.6.0+cpu
+torch==2.6.0+cpu; platform_machine == "x86_64" # torch>2.6.0+cpu has performance regression on x86 platform, see https://github.com/pytorch/pytorch/pull/151218
+torch==2.8.0; platform_machine == "ppc64le" or platform_machine == "aarch64" or platform_system == "Darwin"
 wheel
 jinja2>=3.1.6
 regex