IB/core: Add rdma netlink helper functions

IB/core: Add rdma netlink helper functions

Orabug: 26124118

This patch adds a function to check if listeners for a netlink multicast
group are present. It also adds a function to receive netlink response
messages.

Signed-off-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: John Fleck <john.fleck@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
(cherry picked from commit bc10ed7d3d19ff61427007b4d7bf98d3e57bb333)

Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>