PCI: Move PCI_FIND_CAP_TTL to pci.h and use it in quirks

Some quirks search for a HyperTransport capability and use a hard-coded TTL
value of 48 to avoid an infinite loop.

Move the definition of PCI_FIND_CAP_TTL to pci.h and use it instead of the
hard-coded TTL values.

[bhelgaas: changelog]
Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/pci.h

@@ -4,6 +4,8 @@
 #define PCI_CFG_SPACE_SIZE	256
 #define PCI_CFG_SPACE_EXP_SIZE	4096
 
+#define PCI_FIND_CAP_TTL	48
+
 extern const unsigned char pcie_link_speed[];
 
 bool pcie_cap_has_lnkctl(const struct pci_dev *dev);