panfrost: Derive texture/sampler_count from shader

panfrost: Derive texture/sampler_count from shader

This avoids a dependency of the shader descriptor on the texture/sampler
state, which simplifies state management. It also fixes pandecode
warnings where textures/samplers are specified but not referenced.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6440>