i965/vs: Rework binding table size calculation.

i965/vs: Rework binding table size calculation.

Unlike the FS, the VS backend already computed the binding table size.
However, it did so poorly: after compilation, it looked to see if any
pull constants/textures/UBOs were in use, and set num_surfaces to the
maximum surface index for that category.  If the VS only used a single
texture or UBO, this overcounted by quite a bit.

The shader time surface was also noted at state upload time (during
drawing), not at compile time, which is inefficient.  I believe it also
had an off by one error.

This patch computes it accurately, while also simplifying the code.

It also renames num_surfaces to binding_table_size, since num_surfaces
wasn't actually the number of surfaces used.  For example, a VS that
used one UBO and no other surfaces would have set num_surfaces to
SURF_INDEX_VS_UBO(1) == 18, rather than 1.  A bit of a misnomer there.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Paul Berry <stereotype441@gmail.com>