re: Make sure re_rxeof() is called in net epoch context
It may pass packets up the stack and so needs to be called in a network
epoch. When a watchdog timeout happens, we need to enter a section
explicitly.
Reviewed by: zlei, glebius, adrian
MFC after: 2 weeks
Sponsored by: Innovate UK
Differential Revision: https://reviews.freebsd.org/D51885