When congestion management is enabled, issue EDC ELS to register congestion
signaling capabilities with the fabric. The response handling will process
the fabric parameters and set the reporting parameters.

Similarly, add support for receiving an EDC request from the fabric
generating a corresponding response.

Implement handlers for congestion signals from the fabric and maintain
statistics for them.

Link: https://lore.kernel.org/r/20210816162901.121235-6-jsmart2021@gmail.comCo-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>