sim: add missing values to array initializers

The sim code has a lot of static initializer for options and devices, but
since they aren't using newer struct style, they have to specify a value
for every option otherwise gcc spits a lot of warnings about "missing
initializer".  So add NULL/0 stubs for pointers/values.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

sim/common/dv-core.c

@@ -113,5 +113,5 @@ dv_core_finish (struct hw *me)
 
 const struct hw_descriptor dv_core_descriptor[] = {
   { "core", dv_core_finish, },
-  { NULL },
+  { NULL, NULL },
 };