WIP: [1/2] Add ELF image support

This PR alongside with the one in pmbootstrap adds support for ELF boot image format used by SONY devices in the years 2012-2013. This PR is basically this PRjust updated.

The reason why the original author did not get it to boot up is mainly new GCC that pmOS uses and missing logo.rle that these devices use to show a logo on boot. Replacing the kernel and adding logo.rle for my pmOS Xperia P port (PR to come once it boots up to OS and kernel is mainlined as CONFIG_VT breaks loading ramdisk on this phone) shows the logo which tells us that this format is correct and that it can be used on these devices.