mesa/st: always use normalized coords for samplers

Normalized samplers is the norm, and non-normalized samplers might cause
some drivers and hardware to have to bend over backwards a bit.

We're using TXF here anyway, so it doesn't really matter what we set
this state to. So let's always use normalized samplers instead of
always using non-normalized samplers. That makes things easier for
everyone.

Fixes: ed0e9862c5 ("st/mesa: implement PBO downloads for ReadPixels")
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17708>
(cherry picked from commit 484205b7eb)

.pick_status.json

@@ -1894,7 +1894,7 @@
         "description": "mesa/st: always use normalized coords for samplers",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "ed0e9862c56d13381f0414b5a835fd31960edfe6"
     },

src/mesa/state_tracker/st_cb_readpixels.c

@@ -159,6 +159,7 @@ try_pbo_readpixels(struct st_context *st, struct gl_renderbuffer *rb,
       struct pipe_sampler_view templ;
       struct pipe_sampler_view *sampler_view;
       struct pipe_sampler_state sampler = {0};
+      sampler.normalized_coords = true;
       const struct pipe_sampler_state *samplers[1] = {&sampler};
 
       u_sampler_view_default_template(&templ, texture, src_format);