mm/migrate: correct kernel-doc notation

Use the expected "Return:" format to prevent a kernel-doc warning.

mm/migrate.c:1157: warning: Excess function parameter 'returns' description in 'next_demotion_node'

Link: https://lkml.kernel.org/r/20210808203151.10632-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/migrate.c

@@ -1149,7 +1149,7 @@ static int node_demotion[MAX_NUMNODES] __read_mostly =
  * next_demotion_node() - Get the next node in the demotion path
  * @node: The starting node to lookup the next node
  *
- * @returns: node id for next memory node in the demotion path hierarchy
+ * Return: node id for next memory node in the demotion path hierarchy
  * from @node; NUMA_NO_NODE if @node is terminal.  This does not keep
  * @node online or guarantee that it *continues* to be the next demotion
  * target.