RDMA/cma: Use existing netif_is_bond_master function

When checking whatever the current netdev is the bond master interface,
use kernel API netif_is_bond_master() instead of hardcoding the check.
No functionality is changed.

Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>