i965: Modify signature to update_texture_surface functions.

i965: Modify signature to update_texture_surface functions.

Previously these functions would accept a pointer to the binding table
and an index indicating which entry in the binding table should be
updated.  Now they merely take a pointer to the binding table entry to
be updated.

This will make it easier to generalize brw_texture_surfaces to support
geometry shaders.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>