net/mlx4_core: Remove counters table allocation from VF flow

Since virtual functions get their counters indices allocation from the PF,
allocate counters indices bitmap only in case the function isn't virtual.

Also, check that the device has counters to allocate before creating the
indices bitmap table.

Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>