ACPI: Update Kconfig help text for items that are no longer modular

The CONTAINER and HOTPLUG_MEMORY options mention modules but are bool
only, so if selected are always built in.

Drop the help text about modules.

Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>