[media] stk1160: remove unneeded check

"card" is a valid pointer here because we checked snd_card_create() for
error returns.  Checking after a dereference makes the static checkers
complain.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Ezequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>