blockdev: fix coding style issues in drive_backup_prepare

Fix a couple of minor coding style issues in drive_backup_prepare.

Signed-off-by: Sergio Lopez <slp@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
1 file changed