drm/xe/tests: Wait for clear fence operation to complete

Ensure the clear operation completes before proceeding, as the clear
fence is not attached to the BO's dma-resv object.

Cc: Matthew Auld <[e-mail]>
Cc: Thomas Hellström <[e-mail]>
Reviewed-by: Matthew Auld <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Signed-off-by: Nirmoy Das <[e-mail]>

drivers/gpu/drm/xe/tests/xe_bo.c

···
 			KUNIT_FAIL(test, "Failed to submit bo clear.\n");
 			return PTR_ERR(fence);
 		}
+
+		if (dma_fence_wait_timeout(fence, false, 5 * HZ) <= 0) {
+			dma_fence_put(fence);
+			KUNIT_FAIL(test, "Timeout while clearing bo.\n");
+			return  -ETIME;
+		}
+
 		dma_fence_put(fence);
 	}