Increase the default number of usb dev nodes to 6. Some new machines

(like the Mac mini) have that many usb devs on board.
ok drahn@ dlg@ miod@

src/etc/MAKEDEV.common

@@ -1,4 +1,4 @@
-vers(a, {-$OpenBSD: MAKEDEV.common,v 1.15 2005/01/28 18:56:27 danh Exp $-})dnl
+vers(a, {-$OpenBSD: MAKEDEV.common,v 1.16 2005/03/01 13:35:59 otto Exp $-})dnl
 divert(1)dnl
 dnl
 dnl Common device definitions.
@@ -175,7 +175,7 @@ dnl
 dnl XXX some arches use ramd, others ramdisk - needs to be fixed eventually
 __devitem(ramdisk, ramdisk, Ramdisk kernel devices,nothing)dnl
 dnl
-target(usb, usb, 0, 1, 2, 3)dnl
+target(usb, usb, 0, 1, 2, 3, 4, 5)dnl
 target(usb, urio, 0)dnl
 twrget(usb, uscan, uscanner, 0)dnl
 target(usb, uhid, 0, 1, 2, 3)dnl