ARM: dts: Add the cpuss property for 8994

The CPUSS property node contains the register that is
used to determine the HW_SOC_VERSION for 8994.
This is required to determine if the 8994_TLBI_WA needs
to be applied.

Change-Id: I75ff9e8618d01d58ec25da442e82ab0b7fbdd17a
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>