arm64: debug: make local symbols static

Make local symbols static, because these are used only in this
file.

Signed-off-by: Jingoo Han <jg1.han@samsung.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: 242c04bc4be959ae28618772e439c27e87a7d880
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>