RDMA/core: Don't call fill_res_entry for PD

None of the drivers implement it, remove it.

Link: https://lore.kernel.org/r/20200623113043.1228482-4-leon@kernel.org
Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>