arm64: mm: fix the function name in comment of cpu_do_switch_mm

Fix the function name of comment of cpu_do_switch_mm,
because cpu_do_switch_mm is the correct name.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-commit: 812944e91dbbfeadaeeb4443a5560a7f45648f0b
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Ian Maund <imaund@codeaurora.org>