RDMA/mlx5: Add the initialization flow to utilize the 'data direct' device

RDMA/mlx5: Add the initialization flow to utilize the 'data direct' device

Add the NET device initialization flow to utilize the 'data
direct' device.

When a NET mlx5_ib device is capable of 'data direct', the following
sequence of actions will occur:
- Find its affiliated 'data direct' VUID via a firmware command.
- Create its own private PD and 'data direct' mkey.
- Register to be notified when its 'data direct' driver is probed or removed.

The DMA device of the affiliated 'data direct' device, including the
private PD and the 'data direct' mkey, will be used later during MR
registrations that request the data direct functionality.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://patch.msgid.link/b11fa87b2a65bce4db8d40341bb6cee490fa4d06.1722512548.git.leon@kernel.org
Signed-off-by: Leon Romanovsky <leon@kernel.org>