selftests: net: lib: Rename ip_addr_add() to adf_*

Rename this function to mark it as autodefer.
For details, see the discussion in the cover letter.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/706327a5db660c7f18ba9fbfba7ce913da065e3e.1758821127.git.petrm@nvidia.com


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