Preliminary irq registration call + irq capability checking

Need to add irqctrl capabilities and irq bits to device memory
caps.

Also need to initialize irq field of devmem caps.

include/l4/api/errno.h

@@ -139,5 +139,6 @@
 #define EACTIVE		132	/* Task active */
 #define ENOIPC		133	/* General IPC error */
 #define ENOCAP		134	/* None or insufficient capability */
+#define ENOUTCB		135	/* Task has no utcb set up */
 
 #endif /* __ERRNO_H__ */