Introduce DEVX to enable direct device commands in downstream patches
from this series.
In that mode of work the firmware manages the isolation between
processes' resources and as such a DEVX user id is created and assigned
to the given user context upon allocation request.
A capability check is done to make sure that this feature is really
supported by the firmware prior to creating the DEVX user id.
Signed-off-by: Yishai Hadas <yishaih@mellanox.com> Signed-off-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>