media: media-device: use strlcpy() instead of strncpy()

gcc-8 reports

drivers/media/media-device.c: In function 'media_device_get_topology':
./include/linux/string.h:245:9: warning: '__builtin_strncpy' specified
bound 64 equals destination size [-Wstringop-truncation]

We need to use strlcpy() to make sure the dest string is nul-terminated.

Signed-off-by: Xiongfeng Wang <xiongfeng.wang@linaro.org>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>