xbmc: hdmi cec supports needs udev for device scanning

libcec support in xbmc compiles without udev being linked to libcec,
but it is useless because xbmc uses libcec´s udev support for scanning
connected CEC devices since:
https://github.com/xbmc/xbmc/commit/59171c7a030f8a9c913abbce931967a6a8ff6897



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>