Staging: hv: fix blkvsc_release() parameters

blkvsc_release() had the wrong parameter list for  struct
block_device_operations

Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Cc: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>