ne2000_isa: make optional

Ignore failure with ne2000_isa device creation.
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

hw/pc.h

@@ -5,6 +5,7 @@
 #include "ioport.h"
 #include "isa.h"
 #include "fdc.h"
+#include "net.h"
 
 /* PC-style peripherals (also used by other machines).  */
 
@@ -176,17 +177,21 @@ void pci_cirrus_vga_init(PCIBus *bus);
 void isa_cirrus_vga_init(void);
 
 /* ne2000.c */
-static inline void isa_ne2000_init(int base, int irq, NICInfo *nd)
+static inline bool isa_ne2000_init(int base, int irq, NICInfo *nd)
 {
     ISADevice *dev;
 
     qemu_check_nic_model(nd, "ne2k_isa");
 
-    dev = isa_create("ne2k_isa");
+    dev = isa_try_create("ne2k_isa");
+    if (!dev) {
+        return false;
+    }
     qdev_prop_set_uint32(&dev->qdev, "iobase", base);
     qdev_prop_set_uint32(&dev->qdev, "irq",    irq);
     qdev_set_nic_properties(&dev->qdev, nd);
     qdev_init_nofail(&dev->qdev);
+    return true;
 }
 
 /* e820 types */