iris: Delete unused iris_screen::aperture_bytes field

This was effectively removed in bb3545a6, but the field wasn't deleted,
leaving it there to troll people.  screen->aperture_bytes is 0?  What?

Fixes: bb3545a6ee ("intel: Store the aperture size in devinfo.")
Reviewed-by: Dave Airlie <airlied@redhat.com>
Tested-by: Mark Janes markjanes@swizzler.org
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18311>
(cherry picked from commit 6a1f7e623f)

.pick_status.json

@@ -7807,7 +7807,7 @@
         "description": "iris: Delete unused iris_screen::aperture_bytes field",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "bb3545a6ee419c4802ac4153eb690a93dc2f339d"
     },

src/gallium/drivers/iris/iris_screen.h

@@ -188,8 +188,6 @@ struct iris_screen {
    unsigned kernel_features;
 #define KERNEL_HAS_WAIT_FOR_SUBMIT (1<<0)
 
-   uint64_t aperture_bytes;
-
    /**
     * Last sequence number allocated by the cache tracking mechanism.
     *