NCSI spec (DSP0222) defines several objects: package, channel, mode,
filter, version and statistics etc. This introduces the data structs
to represent those objects and implement functions to manage them.
Also, this introduces CONFIG_NET_NCSI for the newly implemented NCSI
stack.

* The user (e.g. netdev driver) dereference NCSI device by
"struct ncsi_dev", which is embedded to "struct ncsi_dev_priv".
The later one is used by NCSI stack internally.
* Every NCSI device can have multiple packages simultaneously, up
to 8 packages. It's represented by "struct ncsi_package" and
identified by 3-bits ID.
* Every NCSI package can have multiple channels, up to 32. It's
represented by "struct ncsi_channel" and identified by 5-bits ID.
* Every NCSI channel has version, statistics, various modes and
filters. They are represented by "struct ncsi_channel_version",
"struct ncsi_channel_stats", "struct ncsi_channel_mode" and
"struct ncsi_channel_filter" separately.
* Apart from AEN (Asynchronous Event Notification), the NCSI stack
works in terms of command and response. This introduces "struct
ncsi_req" to represent a complete NCSI transaction made of NCSI
request and response.

link: https://www.dmtf.org/sites/default/files/standards/documents/DSP0222_1.1.0.pdf
Signed-off-by: Gavin Shan
Acked-by: Joel Stanley
Signed-off-by: David S. Miller