iwlegacy: Use PCI Express Capability accessors

Use PCI Express Capability access functions to simplify iwlegacy driver.

[bhelgaas: split iwlegacy, iwlwifi, rtlwifi into separate patches]
Signed-off-by: NJiang Liu <jiang.liu@huawei.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/net/wireless/iwlegacy/common.h

@@ -1832,10 +1832,8 @@ int il_enqueue_hcmd(struct il_priv *il, struct il_host_cmd *cmd);
 static inline u16
 il_pcie_link_ctl(struct il_priv *il)
 {
-	int pos;
 	u16 pci_lnk_ctl;
-	pos = pci_pcie_cap(il->pci_dev);
-	pci_read_config_word(il->pci_dev, pos + PCI_EXP_LNKCTL, &pci_lnk_ctl);
+	pcie_capability_read_word(il->pci_dev, PCI_EXP_LNKCTL, &pci_lnk_ctl);
 	return pci_lnk_ctl;
 }