Voluntarily add myself as maintainer for Smartfusion2

Signed-off-by: Subbaraya Sundeep <sundeep.lkml@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 1510552520-3566-1-git-send-email-sundeep.lkml@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>