EDAC: Add routine to check if MC devices list is empty

We need to know if any MC devices have been allocated.

Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/1485537863-2707-7-git-send-email-Yazen.Ghannam@amd.com


[ Prettify text. ]
Signed-off-by: Borislav Petkov <bp@suse.de>