Changes to the LRO code have exposed a bug in iflib where devices which are not capable of doing LRO are still calling tcp_lro_flush_all(), even when they have not initialized the LRO context. This used to be mostly harmless, but the LRO code now sets the VNET based on the ifp in the lro context and will try to access it through a NULL ifp resulting in a panic at boot.
This patch unconditionally initializes LRO so that we have a valid LRO context when calling tcp_lro_flush_all(). One alternative is to check the device capabilities before calling tcp_lro_flush_all() or adding a new state flag in the ctx. However, it seems unwise to add an extra, mostly useless test for higher performance devices when we can just initialize LRO for all devices.