Driver mapping refactory.

VFS CHANGES:
- dmap table no longer statically initialized in VFS
- Dropped FSSIGNON svrctl call no longer used by INET

INET CHANGES:
- INET announces its presence to VFS just like any other driver

RS CHANGES:
- The boot image dev table contains all the data to initialize VFS' dmap table
- RS interface supports asynchronous up and update operations now
- RS interface extended to support driver style and flags

include/unistd.h

@@ -191,7 +191,7 @@ _PROTOTYPE( int getnprocnr, (pid_t pid)					);
 _PROTOTYPE( int getpprocnr, (void)					);
 _PROTOTYPE( int _pm_findproc, (char *proc_name, int *proc_nr)		);
 _PROTOTYPE( int mapdriver, (char *label, int major, int style,
-							int force)	);
+							int flags)	);
 _PROTOTYPE(int adddma, (endpoint_t proc_e,
 				phys_bytes start, phys_bytes size)	);
 _PROTOTYPE(int deldma, (endpoint_t proc_e,