block: Reuse reference handling from bdrv_open() Remove the reference parameter and the related handling code from bdrv_file_open(), since it exists in bdrv_open() now as well. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>