cifs: fix session state check in reconnect to avoid use-after-free issue

cifs: fix session state check in reconnect to avoid use-after-free issue

[ Upstream commit 99f280700b4cc02d5f141b8d15f8e9fad0418f65 ]

Don't collect exiting session in smb2_reconnect_server(), because it
will be released soon.

Note that the exiting session will stay in server->smb_ses_list until
it complete the cifs_free_ipc() and logoff() and then delete itself
from the list.

Signed-off-by: Winston Wen <wentao@uniontech.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>