armv9a/tune: Add the support for the Neoverse N2 core

This adds the support for the Neoverse N2 core, even though the
Neoverse N2 core implements the Arm v9.0-A architecture, but the support
of it in GCC is based on the Arm v8.5-A architecture. Please see the
commit 50d9db203bc3 ("aarch64: Add support for Neoverse N2 CPU") in GCC
for more detail.

(From OE-Core rev: 37597397)

Signed-off-by: Kevin Hao <kexin.hao@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
[Kevin: Convert to the old style override syntax]
Signed-off-by: Kevin Hao <kexin.hao@windriver.com>
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>