cifs: when a channel is not found for server, log its connection id

cifs_ses_get_chan_index gets the index for a given server pointer.
When a match is not found, we warn about a possible bug.
However, printing details about the non-matching server could be
more useful to debug here.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>