Revert "linux: fix reporting NL_RTM_DELLINK to Netlink sockets"

I received a report that certain Linux application would crash on a
message of a departure of an interface with FreeBSD name. Looks like
dropping NL_RTM_DELLINK is a lesser evil than relay them with FreeBSD
names.

This reverts commit 554907bac3b264863a051f75eedc35d180d3e18c.