Allow BLKIOMIN and BLKALIGNOFF to super device in update_engine.

These ioctls are similar to BLKGETSIZE64; they return benign information
about the partition's alignment, and are used by liblp to optimally
align dynamic partition extents.

The system_block_device is included here because on retrofit devices,
the "super" partition is mapped to the system partition.

Test: manual OTA on retrofit device
Bug: 118506262
Change-Id: I3dd3c99d86d63f97bcd393cff374e27f5ed2da2e