aarch64: Add supports for FEAT_PoPS feature and DC instructions.

aarch64: Add supports for FEAT_PoPS feature and DC instructions.

This patch add support for FEAT_PoPS feature which can be enabled
through +pops command line flag.

This patch also adds support for following DC instructions and the
spec can be found here [1].
1. "dc cigdvaps" enabled on passing +memtag+pops command line flags.
2. "dc civaps" enabled on passing +pops command line flag.

[1]: https://developer.arm.com/documentation/ddi0601/2025-03/AArch64-Instructions?lang=en