Merge branch 'neighbor-More-gc_list-changes'

David Ahern says:

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neighbor: More gc_list changes

More gc_list changes and cleanups.

The first 2 patches are bug fixes from the first gc_list change.
Specifically, fix the locking order to be consistent - table lock
followed by neighbor lock, and then entries in the FAILED state
should always be candidates for forced_gc without waiting for any
time span (return to the eviction logic prior to the separate gc_list).

Patch 3 removes 2 now unnecessary arguments to neigh_del.

Patch 4 moves a helper from a header file to core code in preparation
for Patch 5 which removes NTF_EXT_LEARNED entries from the gc_list.
These entries are already exempt from forced_gc; patch 5 removes them
from consideration and makes them on par with PERMANENT entries given
that they are also managed by userspace.
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Signed-off-by: David S. Miller <davem@davemloft.net>