mlxsw: spectrum: Better represent KVDL partitions

The KVD linear (KVDL) allocator currently consists of a very large
bitmap that reflects the KVDL's usage. The boundaries of each partition
as well as their allocation size are represented using defines.

This representation requires us to patch all the functions that act on a
partition whenever the partitioning scheme is changed. In addition, it
does not enable the dynamic configuration of the KVDL using the
up-coming resource manager.

Add objects to represent these partitions as well as the accompanying
code that acts on them to perform allocations and de-allocations.

In the following patches, this will allow us to easily add another
partition as well as new operations to act on these partitions.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>