IPA HAL: fix the upstream down issue

When upstream interface went down but
tethered interface still up, send "NULL"
upstream iface name to IPACM to clean up
previous up upstream interface.

Bug: 67396342

Change-Id: Ic586072721f9a053126ae0e6a54a00c196632a35
1 file changed
tree: 0b43e1d0f643331524683d331b6e70a6426a9964
  1. hal/
  2. ipacm/
  3. ipanat/
  4. configure.ac
  5. Makefile.am