bonding: trivial: remove unused variables

Get rid of these:
drivers/net/bonding//bond_main.c: In function ‘bond_update_slave_arr’:
drivers/net/bonding//bond_main.c:3754:6: warning: variable
‘slaves_in_agg’ set but not used [-Wunused-but-set-variable]
  int slaves_in_agg;
      ^
  CC [M]  drivers/net/bonding//bond_3ad.o
drivers/net/bonding//bond_3ad.c: In function
‘ad_marker_response_received’:
drivers/net/bonding//bond_3ad.c:1870:61: warning: parameter ‘marker’
set but not used [-Wunused-but-set-parameter]
 static void ad_marker_response_received(struct bond_marker *marker,
                                                             ^
drivers/net/bonding//bond_3ad.c:1871:19: warning: parameter ‘port’ set
but not used [-Wunused-but-set-parameter]
      struct port *port)
                   ^

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>