net: caif: Drop unnecessary NULL check after container_of

The first parameter passed to chnl_recv_cb() can never be NULL since all
callers dereferenced it. Consequently, container_of() on it is also never
NULL, even though the reference into the structure points to the first
element of the structure. The NULL check is therefore unnecessary.
On top of that, it is misleading to perform a NULL check on the result of
container_of() because the position of the contained element could change,
which would make the test invalid. Remove the unnecessary NULL check.

This change was made automatically with the following Coccinelle script.

@@
type t;
identifier v;
statement s;
@@

<+...
(
  t v = container_of(...);
|
  v = container_of(...);
)
  ...
  when != v
- if (\( !v \| v == NULL \) ) s
...+>

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>