x86: pci: Allow binding of some devices before relocation

At present only bridge devices are bound before relocation, to save space
in pre-relocation memory. In some cases we do actually want to bind a
device, e.g. because it provides the console UART. Add a devicetree
binding to support this.

Use the PCI_VENDEV() macro to encode the cell value. This is present in
U-Boot but not used, so move it to the binding header-file.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

doc/device-tree-bindings/pci/x86-pci.txt

@@ -20,6 +20,10 @@ For PCI devices the following optional property is available:
 	output to be lost. This should not generally be used in production code,
 	although it is often harmless.
 
+- u-boot,pci-pre-reloc : List of vendor/device IDs to bind before relocation, even
+	if they are not bridges. This is useful if the device is needed (e.g. a
+	UART). The format is 0xvvvvdddd where d is the device ID and v is the
+	vendor ID.
 
 Example:
 
@@ -32,7 +36,8 @@ pci {
 		0x42000000 0x0 0xb0000000 0xb0000000 0 0x10000000
 		0x01000000 0x0 0x1000 0x1000 0 0xefff>;
 	u-boot,skip-auto-config-until-reloc;
-
+	u-boot,pci-pre-reloc = <
+		PCI_VENDEV(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_APL_UART2)>;
 
 	serial: serial@18,2 {
 		reg = <0x0200c210 0 0 0 0>;