[Docs] Fix code example errors in API docs (paddle.device, paddle.diagonal) (#7791)

Co-authored-by: cutetocute <jiuwoxiao@outlook.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 3 people

docs/api/paddle/device/max_memory_reserved_cn.rst

@@ -25,4 +25,4 @@ max_memory_reserved
     >>> paddle.device.max_memory_reserved('npu:0')
     >>> paddle.device.max_memory_reserved('npu')
     >>> paddle.device.max_memory_reserved(0)
-    >>> paddle.device.max_memory_reserved(Paddle.CustomPlace('npu',0))
+    >>> paddle.device.max_memory_reserved(paddle.CustomPlace('npu', 0))

docs/api/paddle/device/memory_allocated_cn.rst

@@ -28,4 +28,4 @@ memory_allocated
     >>> paddle.device.memory_allocated('npu:0')
     >>> paddle.device.memory_allocated('npu')
     >>> paddle.device.memory_allocated(0)
-    >>> paddle.device.memory_allocated(Paddle.CustomPlace('npu',0))
+    >>> paddle.device.memory_allocated(paddle.CustomPlace('npu', 0))

docs/api/paddle/device/memory_reserved_cn.rst

@@ -25,4 +25,4 @@ memory_reserved
     >>> paddle.device.memory_reserved('npu:0')
     >>> paddle.device.memory_reserved('npu')
     >>> paddle.device.memory_reserved(0)
-    >>> paddle.device.memory_reserved(Paddle.CustomPlace('npu',0))
+    >>> paddle.device.memory_reserved(paddle.CustomPlace('npu', 0))