arch/x86/kernel/apic/apic_flat_64.c: Make comment match the code

Make the comment match the code, this also holds for intel systems,
according to probe_64.c in the same directory.
Signed-off-by: Jasper Spaans <spaans@fox-it.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

arch/x86/kernel/apic/apic_flat_64.c

@@ -223,7 +223,7 @@ struct apic apic_flat =  {
 };
 
 /*
- * Physflat mode is used when there are more than 8 CPUs on a AMD system.
+ * Physflat mode is used when there are more than 8 CPUs on a system.
  * We cannot use logical delivery in this case because the mask
  * overflows, so use physical mode.
  */