fdts: stm32mp15: enable early watchdog interrupt

Enable watchdog secure interrupt to dump registers in case
of non secure watchdog.

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Change-Id: Icc9c32125af389df01215687ca915ea67023cda3
Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/tf-a/+/186542


Reviewed-by: CITOOLS <smet-aci-reviews@lists.codex.cro.st.com>
Reviewed-by: Yann GAUTIER <yann.gautier@st.com>