drivers: acpi: Fix dependency for ACPI_HOTPLUG_CPU

Fix the following build warning:

warning: (ACPI_HOTPLUG_CPU) selects ACPI_CONTAINER which has unmet direct dependencies (ACPI && EXPERIMENTAL)

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Len Brown <len.brown@intel.com>