selftests: net: vlan_bridge_binding: Rename dfr_set_binding_*() to adf_*

This test contains two autodefer-like helpers, but namespaces them as dfr_*
instead of adf_* like this patchset. Rename them.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/5f0c81b39e9e1f56f706cc4b53f82238a1d1e2f9.1758821127.git.petrm@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>