Add support to download SYSFW into internal RAM via DFU in DFU boot
mode. Prepare a DFU config entity entry dynamically using buffer address
allocated for SYSFW and start DFU gadget to get SYSFW.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>