edac: tag sb_edac as EXPERIMENTAL, as it requires more testing

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/edac/Kconfig

@@ -215,6 +215,7 @@ config EDAC_I7300
 config EDAC_SBRIDGE
 	tristate "Intel Sandy-Bridge Integrated MC"
 	depends on EDAC_MM_EDAC && PCI && X86 && X86_MCE_INTEL
+	depends on EXPERIMENTAL
 	help
 	  Support for error detection and correction the Intel
 	  Sandy Bridge Integrated Memory Controller.