pci: pcie_dw_common: introduce pcie_dw_find_capability()

Add PCIe config space capability search function specific for
the host controller, which are bridges *to* PCI devices but
are not PCI devices themselves.

Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20241125-topic-pcie-controller-v1-1-45c20070dd53@linaro.org
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
diff --git a/drivers/pci/pcie_dw_common.h b/drivers/pci/pcie_dw_common.h
index e0f7796..8cb99a1 100644
--- a/drivers/pci/pcie_dw_common.h
+++ b/drivers/pci/pcie_dw_common.h
@@ -139,6 +139,8 @@
 int pcie_dw_write_config(struct udevice *bus, pci_dev_t bdf, uint offset, ulong value,
 			 enum pci_size_t size);
 
+u8 pcie_dw_find_capability(struct pcie_dw *pci, u8 cap);
+
 static inline void dw_pcie_dbi_write_enable(struct pcie_dw *pci, bool en)
 {
 	u32 val;