block/blkreplay: Remove protocol-related fields

block/blkreplay: Remove protocol-related fields

The blkreplay driver is not a protocol so it should implement bdrv_open
instead of bdrv_file_open and not provide a protocol_name.

Attempts to invoke this driver using protocol syntax
(i.e. blkreplay:<filename:options:...>) will now fail gracefully:

  $ qemu-img info blkreplay:foo
  qemu-img: Could not open 'blkreplay:foo': Unknown protocol 'blkreplay'

Signed-off-by: Fabiano Rosas <[email protected]>
Reviewed-by: Pavel Dovgalyuk <[email protected]>
Reviewed-by: Max Reitz <[email protected]>
Signed-off-by: Kevin Wolf <[email protected]>