[media] ati_remote: avoid fragile snprintf use

Passing overlapping source and destination to snprintf is
fragile. Replace with a single (mostly) equivalent call. If one wants
to preserve the space preceding udev->product whether or not there was
a manufacturer, just remove udev->manufacturer from the && expression.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>