ols: fixed parallel stage triggers

Stage count was always getting incremented one more than
actual stages, and this caused a extra stage with zero'ed data
probe lines to have the start bit field.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>

hardware/openbench-logic-sniffer/protocol.c

@@ -99,7 +99,7 @@ SR_PRIV int ols_configure_probes(const struct sr_dev_inst *sdi)
 				return SR_ERR;
 		}
 		if (stage > devc->num_stages)
-			devc->num_stages = stage;
+			devc->num_stages = stage - 1;
 	}
 
 	return SR_OK;