staging: unisys: return error value directly

In case of error we are jumping to err_del_scsipending_ent and always
returning SCSI_MLQUEUE_DEVICE_BUSY from error path. We donot need a
variable to return a fixed error value, it can be returned directly.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>