examples/power: add FIFO per core for JSON interface

examples/power: add FIFO per core for JSON interface

This patch implements a separate FIFO for each cpu core to improve the
previous functionality where anyone with access to the FIFO could affect
any core on the system. By using appropriate permissions, FIFO interfaces
can be configured to only affect the particular cores.

Because each FIFO is per core, the following fields have been removed
from the command JSON format: core_list, resource_id, name.

Signed-off-by: Lukasz Krakowiak <lukaszx.krakowiak@intel.com>
Signed-off-by: Lukasz Gosiewski <lukaszx.gosiewski@intel.com>
Signed-off-by: Marcin Hajkowski <marcinx.hajkowski@intel.com>
Tested-by: David Hunt <david.hunt@intel.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>