The old 'ip addr flush' logic had several flaws:

* It reversed logic for primary v/s secondary flags
  (though, it sort of worked right anyway)

* The code tried to remove secondaries and then primaries,
  but in practice, it always removed one primary per loop,
  which not at all efficient.

* The filter logic in the core would run only the first
  filter in most cases.

* If you used '-s -s', the ifa_flags member would be
  modified, which could make future filters fail
  to function fine.

This patch attempts to fix all of these issues.
Tested-by: Brian Haley <brian.haley@hp.com>
Signed-off-by: Ben Greear <greearb@candelatech.com>