panfrost: Expose PIPE_CAP_SHAREABLE_SHADERS

Now that the compile entrypoints don't touch the context, it's clear
that we can support this. Note, even though the pools for shaders and
descriptors are referenced from particular contexts, they are unowned
pools -- once uploaded, any thread can use the results.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10976>

src/gallium/drivers/panfrost/pan_screen.c

@@ -307,9 +307,6 @@ panfrost_get_param(struct pipe_screen *screen, enum pipe_cap param)
         case PIPE_CAP_NIR_IMAGES_AS_DEREF:
                 return 0;
 
-        case PIPE_CAP_SHAREABLE_SHADERS:
-                return 0;
-
         case PIPE_CAP_DRAW_INDIRECT:
                 return has_heap && is_deqp;