Move cper.c from drivers/acpi/apei to drivers/firmware/efi

cper.c contains code to decode and print "Common Platform Error Records".
Originally added under drivers/acpi/apei because the only user was in that
same directory - but now we have another consumer, and we shouldn't have
to force CONFIG_ACPI_APEI get access to this code.

Since CPER is defined in the UEFI specification - the logical home for
this code is under drivers/firmware/efi/

Acked-by: Matt Fleming <matt.fleming@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 252f0e8..08eadb4 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -374,7 +374,9 @@
 
 config ACPI_EXTLOG
 	tristate "Extended Error Log support"
-	depends on X86_MCE && ACPI_APEI
+	depends on X86_MCE
+	select EFI
+	select UEFI_CPER
 	default n
 	help
 	  Certain usages such as Predictive Failure Analysis (PFA) require