net/mlx4_core: Adjust counter grant policy in the resource tracker

Each physical function has a guarantee of two counters per port, one
for a default counter and one for the IB driver.

Each virtual function has a guarantee of one counter per port.
All other counters are free and can be obtained on demand.

This is a preparation step for supporting a get_vf_stats ndo call,
so we can promise a counter for every VF in order to collect their
statistics from the PF context.

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>