arm: mach-k3: j7200: Add support for storing extended boot info from ROM

Starting J7200 SoC, ROM supports for loading sysfw directly from boot
image. ROM passes this information on number of images that are loaded
to bootloader at certain location. Add support for storing this
information before it gets corrupted.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Suman Anna <s-anna@ti.com>