implemented hook_interrupt() in PCI code

enabled PCI interrupts
ohci seems to damage something in PCI config -> PCI device enumeration 
does not top with latest device
networking in EmuTOS lost (probably a result of PCI interrupt
implementation)

include/wait.h

@@ -44,6 +44,8 @@
 typedef bool (*checker_func)(void);
 
 extern void wait(uint32_t);
+extern void wait_us(uint32_t);  /* this is just an alias to the above */
+
 inline static void udelay(long us)
 {
     wait((uint32_t) us);