V4L/DVB (10293): uvcvideo: replace strn{cpy,cat} with strl{cpy,cat}.

strncpy is unsafe as it doesn't append a terminating NUL character when the
source string doesn't fit in the destination buffer. Replace it with strlcpy.
strncat is misused as its size argument refers to the source string, not the
destination buffer. Replace it with strlcat.

Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>