[Intel-gfx] Cleanups and user buffer object for vb [0/6]

[Carl Worth]

Here's a simple patch series that starts with some boring cleanups,
(mostly just simple renamings with no functional changes), and a
final commit that adds a new buffer object for the vertex buffer.

Still to come is similar treatment for the surface state and binding
table. But I wanted to send this out now to ensure I'm on the
right track and that I'm driving git-send-email properly.

There's no notable performance improvement here. In fact there's
some slowdown. We're not worried about this now as we're laying
the groundwork to be able to move to UXA with buffer objects for
pixmaps, and *then* we should be able to get some performance.