MAINTAINERS: chenhc@lemote.com -> chenhuacai@kernel.org

Use @kernel.org address as the main communications end point. Update the
corresponding M-entries and .mailmap (for git shortlog translation).

Signed-off-by: Huacai Chen <chenhuacai@kernel.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <1607160121-9977-1-git-send-email-chenhuacai@kernel.org>