dm: pci: Add a function to read a PCI BAR

At present PCI address transaction is not supported so drivers must
manually read the correct BAR after reading the device tree info. The
ns16550 has a suitable implementation, so move this code into the core
DM support.

Note that there is no live-tree equivalent at present.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: correct the unclear comments in test.dts]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/include/dm/fdtaddr.h b/include/dm/fdtaddr.h
index 57b326c..959d3bc 100644
--- a/include/dm/fdtaddr.h
+++ b/include/dm/fdtaddr.h
@@ -138,4 +138,12 @@
 fdt_addr_t devfdt_get_addr_size_name(struct udevice *dev, const char *name,
 				     fdt_size_t *size);
 
+/**
+ * devfdt_get_addr_pci() - Read an address and handle PCI address translation
+ *
+ * @dev: Device to read from
+ * @return address or FDT_ADDR_T_NONE if not found
+ */
+fdt_addr_t devfdt_get_addr_pci(struct udevice *dev);
+
 #endif