ACPI: Add an interface to evaluate _OST

Added acpi_evaluate_hotplug_opt(). All ACPI hotplug handlers must call
this function when evaluating _OST for hotplug operations. If the
platform does not support _OST, this function returns AE_NOT_FOUND and
has no effect on the platform.

ACPI_HOTPLUG_OST is defined when all relevant ACPI hotplug operations,
such as CPU, memory and container hotplug, are enabled. This assures
consistent behavior among the hotplug operations with regarding the
_OST support. When ACPI_HOTPLUG_OST is not defined, this function is
a no-op.

ACPI PCI hotplug is not enhanced to support _OST at this time since it
is a legacy method being replaced by PCIe native hotplug. _OST support
for ACPI PCI hotplug may be added in future if necessary.

Some platforms may require the OS to support _OST in order to support
ACPI hotplug operations. For example, if a platform has the management
console where user can request a hotplug operation from, this _OST
support would be required for the management console to show the result
of the hotplug request to user.

Added macro definitions of _OST source events and status codes.
Also renamed OSC_SB_CPUHP_OST_SUPPORT to OSC_SB_HOTPLUG_OST_SUPPORT
since this _OSC bit is not specific to CPU hotplug. This bit is
defined in Table 6-147 of ACPI 5.0 as follows.

  Bits:       3
  Field Name: Insertion / Ejection _OST Processing Support
  Definition: This bit is set if OSPM will evaluate the _OST
              object defined under a device when processing
              insertion and ejection source event codes.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>