Remove unnecessary check in parsing

Test: build hidl-gen, hidl_test
Change-Id: Ice98994fa7c907d3a38ce5b3ea64f082decff697
diff --git a/hidl-gen_y.yy b/hidl-gen_y.yy
index 5480ac3..cf6b090 100644
--- a/hidl-gen_y.yy
+++ b/hidl-gen_y.yy
@@ -952,7 +952,6 @@
 annotated_compound_declaration
     : opt_annotations compound_declaration
       {
-          CHECK($2 != nullptr);
           $2->setAnnotations($1);
           $$ = $2;
       }