cifs: reconnect helper should set reconnect for the right channel

We introduced a helper function to be used by non-cifsd threads to
mark the connection for reconnect. For multichannel, when only
a particular channel needs to be reconnected, this had a bug.

This change fixes that by marking that particular channel
for reconnect.

Fixes: dca65818 ("cifs: use a different reconnect helper for non-cifsd threads")
Cc: stable@vger.kernel.org
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>