arm: dts: k3-*-binman: Move to using templated FITs

Reduce redundancy in code by using templates to generate the A72 boot
binaries (tispl.bin and u-boot.img) as well as R5 boot binary sysfw.itb
(for legacy boot following devices J721E and AM65x).

Signed-off-by: Neha Malcom Francis <n-francis@ti.com>
Acked-by: Andrew Davis <afd@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Manorit Chawdhry <m-chawdhry@ti.com>