thermal: intel: hfi: Refactor enabling code into helper functions

[ Upstream commit 8a8b6bb9 ]

In preparation for the addition of a suspend notifier, wrap the logic to
enable HFI and program its memory buffer into helper functions. Both the
CPU hotplug callback and the suspend notifier will use them.

This refactoring does not introduce functional changes.

Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Stable-dep-of: 97566d09 ("thermal: intel: hfi: Add syscore callbacks for system-wide PM")
Signed-off-by: Sasha Levin <sashal@kernel.org>