cifs: Remove unused cEVENT macro

It uses an undefined KERN_EVENT and is itself unused.

Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
Signed-off-by: Steve French <smfrench@gmail.com>