EDAC, skx: Fix randconfig builds

The driver depends on the ADXL component glue and selects it. However,
ADXL itself implicitly depends on ACPI and in nonsensical randconfig
builds like this:

  # CONFIG_ACPI is not set
  CONFIG_ACPI_ADXL=y

where ACPI is not enabled, the build fails with:

  drivers/edac/skx_edac.o: In function `skx_mce_check_error':
  skx_edac.c:(.text+0xab): undefined reference to `adxl_decode'
  drivers/edac/skx_edac.o: In function `skx_init':
  skx_edac.c:(.init.text+0x8bf): undefined reference to `adxl_get_component_names'
  make: *** [vmlinux] Error 1

Add stubs for that case so that the build succeeds. CONFIG_ACPI=n
doesn't make any sense for real configurations but this fix will at
least silence randconfig builds.
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Tony Luck <tony.luck@intel.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>

drivers/edac/Kconfig

@@ -234,7 +234,7 @@ config EDAC_SKX
 	depends on PCI && X86_64 && X86_MCE_INTEL && PCI_MMCONFIG
 	depends on ACPI_NFIT || !ACPI_NFIT # if ACPI_NFIT=m, EDAC_SKX can't be y
 	select DMI
-	select ACPI_ADXL
+	select ACPI_ADXL if ACPI
 	help
 	  Support for error detection and correction the Intel
 	  Skylake server Integrated Memory Controllers. If your

include/linux/adxl.h

@@ -7,7 +7,12 @@
 #ifndef _LINUX_ADXL_H
 #define _LINUX_ADXL_H
 
+#ifdef CONFIG_ACPI_ADXL
 const char * const *adxl_get_component_names(void);
 int adxl_decode(u64 addr, u64 component_values[]);
+#else
+static inline const char * const *adxl_get_component_names(void)  { return NULL; }
+static inline int adxl_decode(u64 addr, u64 component_values[])   { return  -EOPNOTSUPP; }
+#endif
 
 #endif /* _LINUX_ADXL_H */