forked from Mirrors/opensbi

Currently, the default payload for FW_PAYLOAD is embedded fw_payload.S itself. This means people have to hack fw_payload.S if they want to have some temporary S-mode test code. This patch adds a separate dummy payload for FW_PAYLOAD which can be easily hacked for some S-mode testing. Signed-off-by: Anup Patel <anup.patel@wdc.com>