Fix etzpc node location in stm32mp157c DTSI file as requested during the
patch review. The comment was addressed then fixup change discarded while
rebasing.

Change-Id: Ie53531fec7da224de0b86c968a66aec441bfc25d
Fixes: 627298d4b655 ("dts: stm32mp157c: add etzpc node")
Reported-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>