EDAC i7core: Use mce socketid for better compatibility

mce->socketid and cpu_data(mce->cpu).phys_proc_id are the same,
compare with mce_setup (in mce.c):
	m->cpu = m->extcpu = smp_processor_id();
        ...
	m->socketid = cpu_data(m->extcpu).phys_proc_id;

This makes it easier for example for XEN patches to hook into
the MCE subsystem.
Compile tested on x86_64.
Signed-off-by: Thomas Renninger <trenn@suse.de>
CC: JBeulich@novell.com
CC: linux-edac@vger.kernel.org
CC: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/edac/i7core_edac.c

@@ -1917,7 +1917,7 @@ static int i7core_mce_check_error(void *priv, struct mce *mce)
 
 #ifdef CONFIG_SMP
 	/* Only handle if it is the right mc controller */
-	if (cpu_data(mce->cpu).phys_proc_id != pvt->i7core_dev->socket)
+	if (mce->socketid != pvt->i7core_dev->socket)
 		return 0;
 #endif