Add code to check if a QP is attached to one or more multicast groups
when destroy_qp is called and return an error if so.

Link: https://lore.kernel.org/r/20220127213755.31697-5-rpearsonhpe@gmail.comSigned-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>