RDMA/rtrs-clt: Fix memory leak of not-freed sess->stats and stats->pcpu_stats

RDMA/rtrs-clt: Fix memory leak of not-freed sess->stats and stats->pcpu_stats

sess->stats and sess->stats->pcpu_stats objects are freed
when sysfs entry is removed. If something wrong happens and
session is closed before sysfs entry is created,
sess->stats and sess->stats->pcpu_stats objects are not freed.

This patch adds freeing of them at three places:
1. When client uses wrong address and session creation fails.
2. When client fails to create a sysfs entry.
3. When client adds wrong address via sysfs add_path.

Fixes: 215378b838df0 ("RDMA/rtrs: client: sysfs interface functions")
Link: https://lore.kernel.org/r/20210528113018.52290-21-jinpu.wang@ionos.com
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>