PCI: Simplify pci_find_(ext_)capability() return value checks

The return value of the pci_find_(ext_)capability() is either zero or the
position of a capability.  It is never negative.

This patch consolidates the form of check from (pos <= 0) to (!pos).
Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/pci.c

@@ -971,7 +971,7 @@ static int pci_save_pcix_state(struct pci_dev *dev)
 	struct pci_cap_saved_state *save_state;
 
 	pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
-	if (pos <= 0)
+	if (!pos)
 		return 0;
 
 	save_state = pci_find_saved_cap(dev, PCI_CAP_ID_PCIX);
@@ -994,7 +994,7 @@ static void pci_restore_pcix_state(struct pci_dev *dev)
 
 	save_state = pci_find_saved_cap(dev, PCI_CAP_ID_PCIX);
 	pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
-	if (!save_state || pos <= 0)
+	if (!save_state || !pos)
 		return;
 	cap = (u16 *)&save_state->cap.data[0];
 
@@ -2158,7 +2158,7 @@ static int _pci_add_cap_save_buffer(struct pci_dev *dev, u16 cap,
 	else
 		pos = pci_find_capability(dev, cap);
 
-	if (pos <= 0)
+	if (!pos)
 		return 0;
 
 	save_state = kzalloc(sizeof(*save_state) + size, GFP_KERNEL);