MSI: Cleanup existing MSI quirks

Move MSI quirks in CONFIG_PCI_MSI, document why the serverworks quirk
does not simply set PCI_BUS_FLAGS_NO_MSI, and create a generic quirk
for other chipsets where setting PCI_BUS_FLAGS_NO_MSI is fine.

Signed-off-by: Brice Goglin <brice@myri.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 08d58fc..6bf327d 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -42,7 +42,7 @@
 /* Lock for read/write access to pci device and bus lists */
 extern struct rw_semaphore pci_bus_sem;
 
-#ifdef CONFIG_X86_IO_APIC
+#ifdef CONFIG_PCI_MSI
 extern int pci_msi_quirk;
 #else
 #define pci_msi_quirk 0