IB/cm: Handle address handle attribute init error

cm_init_av_by_path depends on ib_init_ah_from_path to initialize ah
attribute and ib_init_ah_from_path() can fail, such error should not
be ignored.

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>