virtio_blk: fix endianess annotations
Since commit 72e61eb40b55dd57031ec5971e810649f82b0259 (virtio: change config
to guest endian) config space is no longer fixed endian.
Lets change the virtio_blk_config variables.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>