arm64: Add Kconfig option for APM X-Gene SOC family

This patch adds arm64/Kconfig option for APM X-Gene SOC family.

Signed-off-by: Kumar Sankaran <ksankaran@apm.com>
Signed-off-by: Loc Ho <lho@apm.com>
Signed-off-by: Feng Kan <fkan@apm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-commit: 159428538323188158a6058956c16c199909d844
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


[imaund@codeaurora.org: resolve merge conflict]
Signed-off-by: Ian Maund <imaund@codeaurora.org>