ir3: Add min gen for multi-mov instructions

swz works on a5xx/a6xx but not a3xx according to CI. I don't have any
access to a4xx HW so I can't tell whether it works there.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11565>

src/freedreno/isa/ir3-cat1.xml

@@ -340,8 +340,10 @@ SOFTWARE.
 		equivalent sequence of mov/cov, but they guarantee that all
 		sources are read before any destination is written, so they
 		behave as-if the moves are executed in parallel.
-		TODO: when were these added?
 	</doc>
+
+	<gen min="500"/> <!-- TODO does a4xx support these? -->
+
 	<field name="SRC0" low="0" high="7" type="#cat1-multi-src">
 		<param name="HALF"/>
 	</field>