python/qemu/console_socket.py: Correct type of recv()

python/qemu/console_socket.py: Correct type of recv()

The type and parameter names of recv() should match socket.socket().

OK, easy enough, but in the cases we don't pass straight through to the
real socket implementation, we probably can't accept such flags. OK, for
now, assert that we don't receive flags in such cases.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 20201006235817.3280413-13-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>