The ethboot configuration inherits splashscreen settings from
am62x_evm_a53_defconfig. Use the prune fragment to disable this
functionality as a baseline before adding targeted splashscreen support
in follow-up commits.
Signed-off-by: Swamil Jain <s-jain1@ti.com> Reviewed-by: Neha Malcom Francis <n-francis@ti.com>