ACPI, APEI, GHES, printk support for recoverable error via NMI

Some APEI GHES recoverable errors are reported via NMI, but printk is
not safe in NMI context.

To solve the issue, a lock-less memory allocator is used to allocate
memory in NMI handler, save the error record into the allocated
memory, put the error record into a lock-less list.  On the other
hand, an irq_work is used to delay the operation from NMI context to
IRQ context.  The irq_work IRQ handler will remove nodes from
lock-less list, printk the error record and do some further processing
include recovery operation, then free the memory.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/apei/Kconfig

@@ -13,6 +13,8 @@ config ACPI_APEI_GHES
 	bool "APEI Generic Hardware Error Source"
 	depends on ACPI_APEI && X86
 	select ACPI_HED
+	select LLIST
+	select GENERIC_ALLOCATOR
 	help
 	  Generic Hardware Error Source provides a way to report
 	  platform hardware errors (such as that from chipset). It