Makefile: drop recursive libcacard clean

Commit eb8eb53e5846a957cf333f2e1ec8cb6e0c04 ("libcacard: rewrite
Makefile in non-recursive style") refactored libcacard/Makefile so it
can be included by the top-level Makefile.

The top-level clean target still loops over subdirectories, including
libcacard/, to invoke recursive clean.  Remove libcacard from the
recursive clean since its files are already included at the top level.
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Makefile

@@ -227,7 +227,7 @@ clean:
 	rm -rf qapi-generated
 	rm -rf qga/qapi-generated
 	$(MAKE) -C tests/tcg clean
-	for d in $(ALL_SUBDIRS) libcacard; do \
+	for d in $(ALL_SUBDIRS); do \
 	if test -d $$d; then $(MAKE) -C $$d $@ || exit 1; fi; \
 	rm -f $$d/qemu-options.def; \
         done