arm64: dts: juno: Add missing MHU secure-irq

[ Upstream commit 422ab8fe ]

The MHU secure interrupt exists physically but is missing in the DT node.

Specify the interrupt in DT node to fix a warning on Arm Juno board:
   mhu@2b1f0000: interrupts: [[0, 36, 4], [0, 35, 4]] is too short

Link: https://lore.kernel.org/r/20220801141005.599258-1-jassisinghbrar@gmail.com


Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>