[TF-M] Change dual-core patch topic name "twincpu" to "dualcpu"

Hi all,

As you know, the current topic for dual-core patches is “twincpu”. In my very own opinion, keyword “twin” implies that the two cores are the same in the system. However, the two cores can be in different archs or even heterogeneous in a dual-core system.

Thus I’d like to propose to change the topic name to “dualcpu” to

* Cover larger scope of dual-core topology/system. * Align with the description in dual PE-based isolation section in TBSA-M spec

Could you please let me know if you have any concern about that change? Any feedback or suggestion is welcome. 😊 Thank you.

Best regards, Hu Ziji