mm/memblock.c: fix wrong comment in __next_free_mem_range()

Remove one redundant "nid" in the comment.
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memblock.c

@@ -566,7 +566,7 @@ int __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size)
 /**
  * __next_free_mem_range - next function for for_each_free_mem_range()
  * @idx: pointer to u64 loop variable
- * @nid: nid: node selector, %MAX_NUMNODES for all nodes
+ * @nid: node selector, %MAX_NUMNODES for all nodes
  * @out_start: ptr to phys_addr_t for start address of the range, can be %NULL
  * @out_end: ptr to phys_addr_t for end address of the range, can be %NULL
  * @out_nid: ptr to int for nid of the range, can be %NULL