rtnl: Add #ifdef CONFIG_RPS around num_rx_queues reference

Commit 76ff5cc9


(rtnl: allow to specify number of rx and tx queues
on device creation) added a reference to the net_device
structure's 'num_rx_queues' member in

	net/core/rtnetlink.c:rtnl_fill_ifinfo()

However, the definition for 'num_rx_queues' is surrounded
by an '#ifdef CONFIG_RPS' while the new reference to it is
not.  This causes a compile error when CONFIG_RPS is not
defined.

Fix the compile error by surrounding the new reference to
'num_rx_queues' by an '#ifdef CONFIG_RPS'.

CC: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>