net/mlx5: DR, ICM pool memory allocator

ICM device memory is used for writing steering rules (STEs) to the NIC.
An ICM memory pool allocator was implemented to manage the required
memory. The pool consists of buckets, a bucket per chunk size.
Once a bucket is empty we will cut a row of memory from the latest
allocated MR, if the MR size is not sufficient we will allocate a new MR.
HW design requires that chunks memory address should be aligned to the
chunk size, this is the reason for managing the MR with row size that
insures memory alignment.
Current design is greedy in memory but provides quick allocation times
in steady state.

Signed-off-by: Alex Vesker <valex@mellanox.com>
Reviewed-by: Erez Shitrit <erezsh@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>