libceph: fix crush_choose_firstn() kernel-doc warnings

Currently, when built with "make W=1", the following warnings are
generated:

net/ceph/crush/mapper.c:466: warning: Function parameter or struct member 'work' not described in 'crush_choose_firstn'
net/ceph/crush/mapper.c:466: warning: Function parameter or struct member 'weight' not described in 'crush_choose_firstn'
net/ceph/crush/mapper.c:466: warning: Function parameter or struct member 'weight_max' not described in 'crush_choose_firstn'
net/ceph/crush/mapper.c:466: warning: Function parameter or struct member 'choose_args' not described in 'crush_choose_firstn'

Update the crush_choose_firstn() kernel-doc to document these
parameters.

Signed-off-by: Jeff Johnson <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Signed-off-by: Ilya Dryomov <[e-mail]>

net/ceph/crush/mapper.c

···
 /**
  * crush_choose_firstn - choose numrep distinct items of given type
  * @map: the crush_map
+ * @work: working space initialized by crush_init_workspace()
  * @bucket: the bucket we are choose an item from
+ * @weight: weight vector (for map leaves)
+ * @weight_max: size of weight vector
  * @x: crush input value
  * @numrep: the number of items to choose
  * @type: the type of item to choose
···
  * @vary_r: pass r to recursive calls
  * @out2: second output vector for leaf items (if @recurse_to_leaf)
  * @parent_r: r value passed from the parent
+ * @choose_args: weights and ids for each known bucket
  */
 static int crush_choose_firstn(const struct crush_map *map,
 			       struct crush_work *work,