V4L/DVB (13414): ttusb-dec: do not overwrite the first part of phys string

Use strlcat() to append a string to the previously created first part.

The semantic match that finds this kind of problem is as follows:
(http://coccinelle.lip6.fr/

)

// <smpl>
@@
expression dev;
expression phys;
expression str;
expression size;
@@
 	usb_make_path(dev, phys, size);
-	strlcpy(phys, str, size);
+	strlcat(phys, str, size);
// </smpl>

Signed-off-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>