Certain platforms like Altera Cyclone V requires a partition with a non-standard partition system-id for the partition from where it reads it's boot loader binary. Currently there is no mechanism in wic to set partition id to an arbitrary value.
Patchset has been sent for review: http://lists.openembedded.org/pipermail/openembedded-core/2016-April/120543.html
Patchset has been merged to oe-core master: http://cgit.openembedded.org/openembedded-core/commit/?id=1a304afea4ad7be12ed5f0fcb397a538345a6b63