[media] ARM: dts: STiH410: update sti-cec for CEC notifier support

To use CEC notifier sti CEC driver needs to get phandle
of the hdmi device.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
CC: Patrice CHOTARD <patrice.chotard@st.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>