i965: Make sampler counts available for the entire drawing operation.

i965: Make sampler counts available for the entire drawing operation.

Previously, we computed sampler counts when generating the SAMPLER_STATE
table.  By computing it earlier, we should be able to shorten a bunch of
loops.

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