glsl: Use sampler_coordinate_components instead of passing it by hand.

glsl: Use sampler_coordinate_components instead of passing it by hand.

We used to pass the number of components actually used for the
coordinate (rather than padding, shadow comparitors, and projectors) by
hand, specifying it on every _texture() call.

The new helper function can just compute this, eliminating a lot of
potential mistakes.

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