Add FNG System logo to fngsystem-image

This is a part of the fix for issue YT-162 "FNG System Logo: Replace in kernel logo with runtime logo or similar"

In this MR:

• added a recipe to install a FNG System logo to eMMC;
• enabled this recipe for fngsystem-image;
• added netpbm and seco-pnmtologo packages to the fngsystem-image. They are needed to convert the previously installed logo file to logo.dat during postinstallation.

Other MRs:

• GUF kernel MR: seco-ne/kernel/linux-guf!320 (merged)
• KUK kernel MR: seco-ne/kernel/linux-imx-kuk!533 (merged)
• meta-seconorth-machine MR: meta-seconorth-machine!578 (merged)