freebsd_iflib: Remove workaround for multi-packet receive.

Following the last commit, we can just let if_input
process the whole chain at once.

The logic here may not have been correct, and possibly
caused memory leaks under high-traffic conditions.

May help with #18585 and others.

freebsd_iflib: Upgrade to that of FreeBSD 13.

ipro1000 still works.

freebsd_iflib: Fix usage of kobj_lookup_method.

Should solve #15441. We should probably enable -Werror=incompatible-ptr
globally to avoid this in the future...

freebsd_iflib: Also NULL-check ctx.

freebsd_iflib: Add NULL check to irq_free.

Should fix #15402.

freebsd_iflib: Synchronize with FreeBSD trunk.

Up through Sep. 20th (yesterday.) Includes some pretty substantial
fixes around MSI interrupts, among other things.

freebsd_iflib: Merge changes from FreeBSD's master branch.

freebsd_iflib: Return the correct filter result in more interrupt handlers.

Confirmed by tqh to fix #14803.

freebsd_iflib: Return the correct filter result in the interrupt handler.

Should fix #14803.

freebsd_iflib: Import.

This is the iflib from FreeBSD 12.0 with a few select patches from
FreeBSD trunk applied (and a lot of #ifdef __HAIKU__s, as you can see.)

There are certain things it adds to SYSINIT that can't be un-initialized
(like the grouptaskqueues), and so rather than adding this to every
driver unnecessarily, a separate .a for it makes the most sense.