RDMA/rtrs: include client and server modules into kernel compilation

Add rtrs Makefile, Kconfig and also corresponding lines into upper layer
infiniband/ulp files.

Link: https://lore.kernel.org/r/20200511135131.27580-14-danil.kipnis@cloud.ionos.com
Signed-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>