dts: update power-states node for ACE 3.0

This patch modifies the DTS files for Intel ADSP ACE 3.0 platforms,
ensuring the power-states node is a child of the cpus node. This change
aligns with Linux conventions and mirrors the adjustments made in commit
e4c43e4c for other platforms.

Signed-off-by: Tomasz Leman <tomasz.m.leman@intel.com>