RDMA/cma: Introduce and use helper functions to init work

Introduce and user helper functions to initialize work for address
resolved and route resolved event that avoid code duplication at few
places.

Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>