Use 'struct pci_device' to note which devices have native drivers.

Remove the check in optionroms.c for CONFIG_ATA and
PCI_CLASS_STORAGE_IDE with a flag in 'struct pci_device'.  This
ensures devices using the ATA driver that aren't in
PCI_CLASS_STORAGE_IDE don't have their optionroms executed.  It also
allows other drivers to disable option rom execution in the future.
diff --git a/src/ata.c b/src/ata.c
index a6b5067..79bc76f 100644
--- a/src/ata.c
+++ b/src/ata.c
@@ -967,6 +967,7 @@
 static void
 init_pciata(struct pci_device *pci, u8 prog_if)
 {
+    pci->have_driver = 1;
     u16 bdf = pci->bdf;
     u8 pciirq = pci_config_readb(bdf, PCI_INTERRUPT_LINE);
     int master = 0;
diff --git a/src/optionroms.c b/src/optionroms.c
index b2415cc..27c172f 100644
--- a/src/optionroms.c
+++ b/src/optionroms.c
@@ -410,9 +410,7 @@
         // Find and deploy PCI roms.
         struct pci_device *pci;
         foreachpci(pci) {
-            u16 v = pci->class;
-            if (v == 0x0000 || v == 0xffff || v == PCI_CLASS_DISPLAY_VGA
-                || (CONFIG_ATA && v == PCI_CLASS_STORAGE_IDE))
+            if (pci->class == PCI_CLASS_DISPLAY_VGA || pci->have_driver)
                 continue;
             init_pcirom(pci, 0, sources);
         }
diff --git a/src/pci.h b/src/pci.h
index f1e3988..a21a1fd 100644
--- a/src/pci.h
+++ b/src/pci.h
@@ -48,6 +48,9 @@
     u8 prog_if, revision;
     u8 header_type;
     u8 secondary_bus;
+
+    // Local information on device.
+    int have_driver;
 };
 extern struct pci_device *PCIDevices;
 extern int MaxPCIBus;