xio: Configure Accelio internal pool

Temporarily hardcoded all 6 allocators + growing quantum and max size
1k allocator - quantum 4k - max 256k
4k allocator - quantum 4k - max 256k
16k allocator - quantum 4k - max 256k
64k allocator - quantum 1k - max 64k
256k allocator - quantum 512 - max 16k
1m allocator - quantum 128 - max 8k

Later we need to calculate the sustainable workload and dynamically
configure Accelio's interal pool accordingly

Signed-off-by: Vu Pham <vu@mellanox.com>
Signed-off-by: Matt Benjamin <matt@cohortfs.com>
xio: Enable Accelio flow control with msgs and bytes throttlers

* Enable Accelio flow control in general
* Read out policy for messages and bytes throttlers from connection's peer_type
* Set Accelio connection flow control with policy throttlers or default values
* Set q_high_mark for xio_connection (80% of queue_depth)

Signed-off-by: Vu Pham <vu@mellanox.com>
Signed-off-by: Matt Benjamin <matt@cohortfs.com>