Remove abandonned capi support for the Mellanox CX4.

This reverts commit 4e56f858.
Signed-off-by: NFrederic Barrat <fbarrat@linux.ibm.com>
Acked-by: NAndrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>