Don't log confusing message on reconnect by default

Change the following message (which can occur on reconnect) from
a warning to an FYI message.  It is confusing to users.

   [58360.523634] CIFS VFS: Free previous auth_key.response = 00000000a91cdc84

By default this message won't show up on reconnect unless the user bumps
up the log level to include FYI messages.

Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>