Add implementation for counter allocator. The ASIC has special memory
pool for various counting purposes. Counter memory is distributed between
equal size banks.

The static sub-pool configuration should specify the following parameters
for each sub-pool:
- Number of required banks.
- Maximum entry size.

Each module can add dedicated sub-pool or use existing one.
Signed-off-by: Arkadi Sharshevsky <arkadis@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>