cifs: change noisy error message to FYI

A customer has reported that their dmesg were being flooded by

  CIFS: VFS: \\server Cancelling wait for mid xxx cmd: a
  CIFS: VFS: \\server Cancelling wait for mid yyy cmd: b
  CIFS: VFS: \\server Cancelling wait for mid zzz cmd: c

because some processes that were performing statfs(2) on the share had
been interrupted due to their automount setup when certain users
logged in and out.

Change it to FYI as they should be mostly informative rather than
error messages.

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>