Remove a bunch of methods that are superseded by if_inc_counter().

Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271783 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Fix the handling of EOP in status descriptors for if_igb(4) and don't
double-free mbufs.

Like ixgbe(4) chipsets, EOP is only set on the final descriptor
in a chain of descriptors.  So, to free the whole list of descriptors,
we should free the current slot _and_ the assembled list of descriptors
that make up the fragment list.

The existing code was setting discard once it saw EOP + an error status;
it then freed all the subsequent descriptors until the next EOP. That's
totally the wrong order.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271784 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f