resin-u-boot.bbclass: Don't deploy image file flags from uboot
resin-u-boot.bbclass: Don't deploy image file flags from uboot

If we do this, these files will only be available if uboot is used. We have
boards (ex. RaspberryPi) which don't use uboot so images will fail while trying
to write these files to boot partition.

Signed-off-by: Andrei Gherzan <8dc7c09356db0b1762fb140617d7375c0a5a4131@resin.io>

resin-os/meta-resin,resin-os/meta-resin,resin-os/meta-resin,resin-os/meta-resin