[BUG] incorrect value of last block in block device protocol for partitions

[Heinrich Schuchardt]

The value for Media.LastBlock of the block IO protocol for partitions is
incorrect for all partitions that do not end on the last block of the
device.

lib/efi_loader/efi_disk.c(448) efi_disk_add_dev():
diskobj->media.last_block = desc->lba - offset;

desc->lba is the end of the disk not of the partition.

Reported-by: Alexander von Gluck IV <kallisti5 at unixzen.com>

Best regards

Heinrich