arm64/dts: gs201: Add AoC S2MPU

AoC is only controlled by TZ.

However, SysMMU has an emulation feature that can be misused to read
from arbitrary memory locations, and with SysMMU under the control of
the kernel, we need to configure S2MPU to block such potentially
malicious transactions.

Add the AoC S2MPU with the new flag “deny-all” which would mainly
unmap the S2MPU interface and configure it to deny all traffic.

Bug: 342511931
Change-Id: I38a1a2af556eaca83be3bd93db1b5dd400034255
Signed-off-by: Mostafa Saleh <smostafa@google.com>