ACPI/PCI: PCI MSI _OSC support capabilities called when root bridge added

The _OSC capability OSC_MSI_SUPPORT is set when the root bridge is added
with pci_acpi_osc_support(), so we no longer need to do it in the PCI
MSI driver.  Also adds the function pci_msi_enabled, which returns true
if pci=nomsi is not on the kernel command-line.

Signed-off-by: Andrew Patterson <andrew.patterson@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/include/linux/pci.h b/include/linux/pci.h
index eae97a2..59a3dc2 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -779,6 +779,10 @@
 
 static inline void pci_restore_msi_state(struct pci_dev *dev)
 { }
+static inline int pci_msi_enabled(void)
+{
+	return 0;
+}
 #else
 extern int pci_enable_msi(struct pci_dev *dev);
 extern void pci_msi_shutdown(struct pci_dev *dev);
@@ -789,6 +793,7 @@
 extern void pci_disable_msix(struct pci_dev *dev);
 extern void msi_remove_pci_irq_vectors(struct pci_dev *dev);
 extern void pci_restore_msi_state(struct pci_dev *dev);
+extern int pci_msi_enabled(void);
 #endif
 
 #ifndef CONFIG_PCIEASPM