RDMA/qedr: Fix incorrect device rate.

Use the correct enum value introduced in commit 12113a35 ("IB/core:
Add HDR speed enum") Prior to this change a 50Gbps port would show 40Gbps.

This patch also cleaned up the redundant redefiniton of ib speeds for
qedr.

Fixes: 12113a35 ("IB/core: Add HDR speed enum")
Signed-off-by: Sagiv Ozeri <sagiv.ozeri@marvell.com>
Signed-off-by: Michal Kalderon <michal.kalderon@marvell.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>