mm: mempolicy: fix kerneldoc of numa_map_to_online_node()

Fix W=1 compile warnings (invalid kerneldoc):

    mm/mempolicy.c:137: warning: Function parameter or member 'node' not described in 'numa_map_to_online_node'
    mm/mempolicy.c:137: warning: Excess function parameter 'nid' description in 'numa_map_to_online_node'
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200728171109.28687-3-krzk@kernel.orgSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/mempolicy.c

@@ -129,7 +129,7 @@ static struct mempolicy preferred_node_policy[MAX_NUMNODES];
 
 /**
  * numa_map_to_online_node - Find closest online node
- * @nid: Node id to start the search
+ * @node: Node id to start the search
  *
  * Lookup the next closest node by distance if @nid is not online.
  */