intel: agilex: Fix psci power domain off

Disable gic cpu interface for powered down cpu. This patch also removes
core reset during power off as core reset will be done during power on

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I2ca96d876b6e71e56d24a9a7e184b6d6226b8673