ibcore: The use of IN_LOOPBACK() now requires a valid VNET context.
Make sure the VNET is set before using this macro.
Fixes: efe58855f3ea2cfc24cb705aabce3bc0fe1fb6d5
PR: 266054
Sponsored by: NVIDIA Networking
(cherry picked from commit f50274674ebf3a51a77708f569d38a238cbad6ec)