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Both kernel and U-Boot use a SMC call to the secure monitor to get the
chip ID. This call is translated by BL31 to a call to the SCP to
retrieve the ID. Add a new SiP call and the backing SCPI command.
Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Change-Id: Ib128f5645ee92866e7ebbcd550dacd33f573524b