UPSTREAM: ARM: 8479/2: add implementation for arm-smccc

UPSTREAM: ARM: 8479/2: add implementation for arm-smccc

Adds implementation for arm-smccc and enables CONFIG_HAVE_SMCCC for
architectures that may support arm-smccc. It's the responsibility of the
caller to know if the SMC instruction is supported by the platform.

Change-Id: Ic7fd73fb040a900cfaa783f70c29b1d984da558b
Reviewed-by: Lars Persson <lars.persson@axis.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
(cherry picked from commit b329f95d70f3f955093e9a2b18ac1ed3587a8f73)