tests: Don't use -@ on plugin de/recompile tests

Using -@ again here obscures what's going on, because at the end we can't
know which run actually generated the symbols node.  We should just
generate the symbols on the first run and leave it at that.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

tests/run_tests.sh

@@ -221,8 +221,8 @@ dtc_overlay_tests () {
     run_test overlay overlay_base.test.dtb overlay_overlay.test.dtb
 
     # test plugin source to dtb and back
-    run_dtc_test -@ -I dtb -O dts -o overlay_overlay_decompile.test.dts overlay_overlay.test.dtb
-    run_dtc_test -@ -I dts -O dtb -o overlay_overlay_decompile.test.dtb overlay_overlay_decompile.test.dts
+    run_dtc_test -I dtb -O dts -o overlay_overlay_decompile.test.dts overlay_overlay.test.dtb
+    run_dtc_test -I dts -O dtb -o overlay_overlay_decompile.test.dtb overlay_overlay_decompile.test.dts
     run_test dtbs_equal_ordered overlay_overlay.test.dtb overlay_overlay_decompile.test.dtb
 
     # test plugin auto-generation without using -@