Remove several layers in the vnode operations vector init code. Declare

Remove several layers in the vnode operations vector init code.  Declare
the operations vector directly instead of via a descriptor array.  Remove
most of the recalculation code, it stopped being needed over a year ago.

This work is similar to what FreeBSD now does, but was developed along a
different line.  Ultimately our vop_ops will become SYSLINK ops for userland
VFS and clustering support.