Revert "can: af_can: fix NULL pointer dereference in can_rx_register()"

This reverts commit afab4655 which is
commit afab4655 upstream.

It is fixing a commit that was reverted from the Android tree due to it
breaking the ABI, so it is not needed here at all.  Revert it now as it
breaks the build.

Fixes: afab4655 ("can: af_can: fix NULL pointer dereference in can_rx_register()")
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: If7235003aab6f625cd81e16e2f21497083fec457