ACPI, APEI, GHES, Prevent GHES to be built as module

GHES (Generic Hardware Error Source) is used to process hardware error
notification in firmware first mode.  But because firmware first mode
can be turned on but can not be turned off, it is unreasonable to
unload the GHES module with firmware first mode turned on.  To avoid
confusion, this patch makes GHES can be enabled/disabled in
configuration time, but not built as module and unloaded at run time.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Len Brown <len.brown@intel.com>