PCI/MSI: Return -ENOSYS for unimplemented interfaces, not -1

Suggested-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Tejun Heo <tj@kernel.org>

include/linux/pci.h

@@ -1156,13 +1156,13 @@ struct msix_entry {
 #ifndef CONFIG_PCI_MSI
 static inline int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec)
 {
-	return -1;
+	return -ENOSYS;
 }
 
 static inline int
 pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec)
 {
-	return -1;
+	return -ENOSYS;
 }
 
 static inline void pci_msi_shutdown(struct pci_dev *dev)
@@ -1177,7 +1177,7 @@ static inline int pci_msix_table_size(struct pci_dev *dev)
 static inline int pci_enable_msix(struct pci_dev *dev,
 				  struct msix_entry *entries, int nvec)
 {
-	return -1;
+	return -ENOSYS;
 }
 
 static inline void pci_msix_shutdown(struct pci_dev *dev)