tisdk-image.bbclass: update for the new rootfs/image infrastructure
tisdk-image.bbclass: update for the new rootfs/image infrastructure

The entire rootfs/image processing infrastructure was rewritten in Python for
Daisy release. Since tisdk_image class is based on rootfs/image base classes
and uses their APIs, some adjustments are required in order for it to work.

Signed-off-by: Denys Dmytriyenko <d29de71aea38aad3a87d486929cb0aad173ae612@ti.com>
Acked-by: Franklin Cooper Jr. <b8c01a1703dc362919183054a071c1f348818c23@ti.com>

rcn-ee/meta-arago,MentorEmbedded/meta-arago,MentorEmbedded/meta-arago,rcn-ee/meta-arago,rcn-ee/meta-arago,MentorEmbedded/meta-arago,rcn-ee/meta-arago,MentorEmbedded/meta-arago,rcn-ee/meta-arago