This reverts commit ddb457c699.
The include rdma/ib_cache.h is kept, and we have to add a memset
to the compat wrapper to avoid compiler warnings in gcc-7
This revert is done to avoid extensive merge conflicts with SMC
changes in netdev during the 4.19 merge window.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>