[pci] Provide PCI_CLASS() to calculate a scalar PCI class value

Rename PCI_CLASS() (which constructs a struct pci_class_id) to
PCI_CLASS_ID(), and provide PCI_CLASS() as a macro which constructs
the 24-bit scalar value of a PCI class code.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/arch/i386/drivers/net/undi.c

 struct pci_driver undipci_driver __pci_driver_fallback = {
 	.ids = undipci_nics,
 	.id_count = ( sizeof ( undipci_nics ) / sizeof ( undipci_nics[0] ) ),
-	.class = PCI_CLASS ( PCI_CLASS_NETWORK, PCI_ANY_ID, PCI_ANY_ID ),
+	.class = PCI_CLASS_ID ( PCI_CLASS_NETWORK, PCI_ANY_ID, PCI_ANY_ID ),
 	.probe = undipci_probe,
 	.remove = undipci_remove,
 };

src/drivers/usb/ehci.c

 struct pci_driver ehci_driver __pci_driver = {
 	.ids = ehci_ids,
 	.id_count = ( sizeof ( ehci_ids ) / sizeof ( ehci_ids[0] ) ),
-	.class = PCI_CLASS ( PCI_CLASS_SERIAL, PCI_CLASS_SERIAL_USB,
-			     PCI_CLASS_SERIAL_USB_EHCI ),
+	.class = PCI_CLASS_ID ( PCI_CLASS_SERIAL, PCI_CLASS_SERIAL_USB,
+				PCI_CLASS_SERIAL_USB_EHCI ),
 	.probe = ehci_probe,
 	.remove = ehci_remove,
 };

src/drivers/usb/xhci.c

 struct pci_driver xhci_driver __pci_driver = {
 	.ids = xhci_ids,
 	.id_count = ( sizeof ( xhci_ids ) / sizeof ( xhci_ids[0] ) ),
-	.class = PCI_CLASS ( PCI_CLASS_SERIAL, PCI_CLASS_SERIAL_USB,
-			     PCI_CLASS_SERIAL_USB_XHCI ),
+	.class = PCI_CLASS_ID ( PCI_CLASS_SERIAL, PCI_CLASS_SERIAL_USB,
+				PCI_CLASS_SERIAL_USB_XHCI ),
 	.probe = xhci_probe,
 	.remove = xhci_remove,
 };

src/include/ipxe/pci.h

 #define PCI_CLASS_SERIAL_USB_EHCI	 0x20	/**< ECHI USB controller */
 #define PCI_CLASS_SERIAL_USB_XHCI	 0x30	/**< xHCI USB controller */
 
+/** Construct PCI class
+ *
+ * @v base		Base class (or PCI_ANY_ID)
+ * @v sub		Subclass (or PCI_ANY_ID)
+ * @v progif		Programming interface (or PCI_ANY_ID)
+ */
+#define PCI_CLASS( base, sub, progif )					\
+	( ( ( (base) & 0xff ) << 16 ) |	( ( (sub) & 0xff ) << 8 ) |	\
+	  ( ( (progif) & 0xff) << 0 ) )
+
 /** A PCI device ID list entry */
 struct pci_device_id {
 	/** Name */
  * @v sub		Subclass (or PCI_ANY_ID)
  * @v progif		Programming interface (or PCI_ANY_ID)
  */
-#define PCI_CLASS(base,sub,progif) {					   \
-	.class = ( ( ( (base) & 0xff ) << 16 ) |			   \
-		   ( ( (sub) & 0xff ) << 8 ) |				   \
-		   ( ( (progif) & 0xff) << 0 ) ),			   \
+#define PCI_CLASS_ID( base, sub, progif ) {				   \
+	.class = PCI_CLASS ( base, sub, progif ),			   \
 	.mask = ( ( ( ( (base) == PCI_ANY_ID ) ? 0x00 : 0xff ) << 16 ) |   \
 		  ( ( ( (sub) == PCI_ANY_ID ) ? 0x00 : 0xff ) << 8 ) |	   \
 		  ( ( ( (progif) == PCI_ANY_ID ) ? 0x00 : 0xff ) << 0 ) ), \