[media] stk1160: warrant a NUL terminated string

strncpy() doesn't warrant a NUL terminated string. Use
strlcpy() instead.

Fixes Coverity bug CID#1195195.

Acked-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>