abitidy: fix data member deduplication element filter

The code now restricts its attention to `class-decl` and `union-decl`
elements, as originally intended, instead of checking every element.

Bug: 266148118
Change-Id: Ib8b9d0bc83996eadf38b2aacf734238913d04590
Signed-off-by: Giuliano Procida <gprocida@google.com>
1 file changed