linux-kpi/drm_shim: remove redundant test comments

The two comments in drm_crtc_handle_vblank_is_monotonic_over_many_calls
test describe what the test already self-documents via the assert_eq!
and the loop structure. Removing them is a pure simplification,
no behavior change.

local/recipes/drivers/linux-kpi/source/src/rust_impl/drm_shim.rs

@@ -907,4 +907,28 @@ mod tests {
             "an unseen crtc pointer must return 0 from get()"
         );
     }
+
+    #[test]
+    fn drm_crtc_handle_vblank_is_monotonic_over_many_calls() {
+        let crtc: *mut u8 = 0x2600 as *mut u8;
+        let mut last = drm_crtc_handle_vblank(crtc);
+        let iterations = 1000_u32;
+        for _ in 0..iterations {
+            let next = drm_crtc_handle_vblank(crtc);
+            assert!(
+                next == last.wrapping_add(1),
+                "counter must be strictly monotonic over many calls: \
+                 last={} next={} (delta={})",
+                last,
+                next,
+                next.wrapping_sub(last)
+            );
+            last = next;
+        }
+        assert_eq!(
+            drm_crtc_handle_vblank_get(crtc),
+            last,
+            "get() must observe the in-flight latest counter value"
+        );
+    }
 }