x86: fix: do not run code in amd_bus.c on non-AMD CPUs

Jan Beulich wrote:

> Even worse - this would even try to access the MSR on non-AMD CPUs
> (currently probably prevented just by the fact that only AMD ones use
> family values of 0x10 or higher).

This patch adds cpu vendor check to the postcore_initcalls.
Reported-by: NJan Beulich <jbeulich@novell.com>
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/pci/amd_bus.c

@@ -555,9 +555,11 @@ static int __init early_fill_mp_bus_info(void)
 	return 0;
 }
 
-postcore_initcall(early_fill_mp_bus_info);
+#else  /* !CONFIG_X86_64 */
 
-#endif
+static int __init early_fill_mp_bus_info(void) { return 0; }
+
+#endif /* !CONFIG_X86_64 */
 
 /* common 32/64 bit code */
 
@@ -583,4 +585,15 @@ static int __init enable_pci_io_ecs(void)
 	return 0;
 }
 
-postcore_initcall(enable_pci_io_ecs);
+static int __init amd_postcore_init(void)
+{
+	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
+		return 0;
+
+	early_fill_mp_bus_info();
+	enable_pci_io_ecs();
+
+	return 0;
+}
+
+postcore_initcall(amd_postcore_init);