arm64: KGDB: Add KGDB config

Add HAVE_ARCH_KGDB for arm64 Kconfig

Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@caviumnetworks.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Git-commit: 9529247db9ecfc5a723e17093614e7437ab0d5bd
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>