Add dependency on generator

FuseSoC requires targets using a generator to depend on it; this
dependency was missing in one of the generators in the test suite. This
isn't caught by the test harness at the moment as these files are not
loaded through the dependency resolution process but injected directly.

tests/capi2_cores/misc/generate.core

@@ -1,8 +1,15 @@
 CAPI=2:
 name : ::generate:0
 
+filesets:
+  default:
+    depend:
+      - generators
+
 targets:
   default:
+    filesets :
+      - default
     generate : [testgenerate_without_params, testgenerate_with_params]
     toplevel : na