RDMA: Add ib_copy_validate_udata_in_cm()

RDMA: Add ib_copy_validate_udata_in_cm()

For structures with comp_mask also absorb the check of comp_mask valid
bits into the helper. This is slightly tricky because ~ might not fully
extend to 64 bits, the helper inserts an explicit type to ensure that ~
covers all bits.

Link: https://patch.msgid.link/r/4-v3-bd56dd443069+49-bnxt_re_uapi_jgg@nvidia.com
Tested-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Acked-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>