IB/mlx5: Remove support for IB_DEVICE_LOCAL_DMA_LKEY

Commit 96249d70 ("IB/core: Guarantee that a local_dma_lkey
is available") allows ULPs that make use of the local dma key to keep
working as before by allocating a DMA MR with local permissions and
converted these consumers to use the MR associated with the PD
rather then device->local_dma_lkey.

ConnectIB has some known issues with memory registration
using the local_dma_lkey (SEND, RDMA, RECV seems to work ok).

Thus don't expose support for it (remove device->local_dma_lkey
setting), and take advantage of the above commit such that no regression
is introduced to working systems.

The local_dma_lkey support will be restored in CX4 depending on FW
capability query.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>