cifs: check only tcon status on tcon related functions

cifs: check only tcon status on tcon related functions

[ Upstream commit 2f0e4f0342201fe2228fcc2301cc2b42ae04b8e3 ]

We had a couple of checks for session in cifs_tree_connect
and cifs_mark_open_files_invalid, which were unnecessary.
And that was done with ses_lock. Changed that to tc_lock too.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Stable-dep-of: 6be2ea33a409 ("cifs: avoid potential races when handling multiple dfs tcons")
Signed-off-by: Sasha Levin <sashal@kernel.org>