platform: template: typo fix in system reboot/shutdown names

This patch does minor typo fix in system reboot/shutdown names
in platform operations.

Signed-off-by: Jiuyang Liu (Sequencer) <liujiuyang1994@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>