ffs_syncvnode: Remove unhelpful print

It can occur during ordinary use of softupdates, or perhaps if writes to the
underlying media fail (causing bufs to be redirtied).  Either way, it is not
particularly actionable.

Reviewed by:	imp, kib
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D16258

sys/ufs/ffs/ffs_vnops.c

@@ -377,10 +377,6 @@ ffs_syncvnode(struct vnode *vp, int waitfor, int flags)
 			wait = !wait;
 			if (wait || ++passes < UFS_NIADDR + 2)
 				goto loop;
-#ifdef INVARIANTS
-			if (!vn_isdisk(vp, NULL))
-				vn_printf(vp, "ffs_fsync: dirty ");
-#endif
 		}
 	}
 	BO_UNLOCK(bo);