Data direct support currently lives in mlx5_ib, which owns the data direct PCI driver, device matching and resource management. To prepare for data direct support in netdev, move this infrastructure to mlx5_core and provide a common interface for its consumers. The series first replaces the direct IB unbind callback with a blocking notifier chain, allowing multiple consumers to receive unbind events. It then separates consumer registration from initialization, consolidates the per-device state and resources, and keeps IB-specific locking and MR teardown in mlx5_ib. With these preparations in place, the final patch moves the shared implementation and PCI driver to mlx5_core. Data direct initialization and resource creation run during core load, before consumers attach; cleanup runs during core unload, after consumers detach. The data direct PCI driver is also explicitly named "mlx5_dd", replacing the previous "mlx5_ib" name derived from KBUILD_MODNAME. This series by Dragos prepares the shared infrastructure for netdev support. The netdev consumer will follow in a separate series. Signed-off-by: Leon Romanovsky <leon@kernel.org>