Correct invalid param in create_volume

There is no argument named "param" in create_volume, besides,
name is not necessary in create_volume(if name is not passed in,
the volume can reach status available with name=null), so this
is to remove param in create_volume in negative tests.

Change-Id: I7e0ed8be728825ca340be584e1dfe0cc5a8dbff5
1 file changed