IB/cma: Fix ports memory leak in cma_configfs

IB/cma: Fix ports memory leak in cma_configfs

The allocated ports structure in never freed. The free function should be
called by release_cma_ports_group, but the group is never released since
we don't remove its default group.

Remove default groups when device group is deleted.

Fixes: b168a25da509 ("IB/cma: Add configfs for rdma_cm")
Link: https://lore.kernel.org/r/20200521072650.567908-1-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@mellanox.com>