init: Regenerate uevents for dependent super partition devices.

This patch adds another uevent-regeneration pass to the first stage
mount. When the super partition spans multiple block devices, we need
/dev/block/by-name symlinks to have been created before we begin mapping
dynamic partitions.

Bug: 116802789
Test: retrofit device boots
Change-Id: I00bb277e1d81385a457c5b4205a95d8fbe365bb2