When CONFIG_RFS_ACCEL or SMP aren't set, we fail to build, fix it.

Also, avoid build warning as of unused function on that setup.

Fixes: c66fa19c ('net/mlx4: Add EQ pool')
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>