arm: mach-k3: common: Add a release_resources_for_core_shutdown() stub

Add a weak release_resources_for_core_shutdown() stub implementation
that can be overridden by actual implementation if a SoC supports that
function.

Signed-off-by: Suman Anna <s-anna@ti.com>
Reviewed-by: Nishanth Menon <nm@ti.com>