ARM: 8480/2: arm64: add implementation for arm-smccc

Adds implementation for arm-smccc and enables CONFIG_HAVE_SMCCC.

Acked-by: Will Deacon <will.deacon@arm.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 14457459)
Signed-off-by: Alex Shi <alex.shi@linaro.org>

Conflicts:
	arch/arm64/kernel/arm64ksyms.c