arm64: add APM X-Gene SoC RTC DTS entry

arm64: add APM X-Gene SoC RTC DTS entry

This patch adds APM X-Gene SoC RTC DTS entry

Signed-off-by: Rameshwar Prasad Sahu <rsahu@apm.com>
Signed-off-by: Loc Ho <lho@apm.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit 7fe2f8776216e25ad7fdb22f3966177777c5022c)
Signed-off-by: Mark Brown <broonie@linaro.org>