EDAC, amd64: Fix improper return value

When the call to zalloc_cpumask_var() fails, returning "false" seems
improper. The real value of macro "false" is 0, and 0 means no error.
Return -ENOMEM instead.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=189071



Signed-off-by: Pan Bian <bianpan2016@163.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/1480831638-5361-1-git-send-email-bianpan201604@163.com


Signed-off-by: Borislav Petkov <bp@suse.de>