caif: checking the wrong variable

In the original code we check if (servl == NULL) twice.  The first time
should print the message that cfmuxl_remove_uplayer() failed and set
"ret" correctly, but instead it just returns success.  The second check
should be checking the value of "ret" instead of "servl".

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Sjur Braendeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>