uboot-phytec

arm: K3: Introduce System Firmware loader framework

Introduce a framework that allows loading the System Firmware (SYSFW)
binary as well as the associated configuration data from an image tree
blob named "sysfw.itb" from an FS-based boot media or from a specific
offset when using a memory device such as SPI flash.

To simplify the handling of and loading from the different boot media
we tap into the existing U-Boot SPL framework usually used for loading
U-Boot by building on an earlier commit that exposes some of that
functionality.

Note that this initial implementation only supports the following boot
modes and renders all other boot modes non-operational:

- FS and RAW-based eMMC/SD card boot
- SPI Flash boot
- Y-Modem based serial boot

Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>