Merge branch 'nps_enet_fixes'

Noam Camus says:

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*** nps_enet fixups ***

Change v2
TX done is handled back with NAPI poll.

Change v1
This patch set is a bunch of fixes to make nps_enet work correctly with
all platforms, i.e. real device, emulation system, and simulation system.
The main trigger for this patch set was that in our emulation system
the TX end interrupt is "edge-sensitive" and therefore we cannot use the
cause register since it is not sticky.
Also:
TX is handled during HW interrupt context and not NAPI job.
race with TX done was fixed.
added acknowledge for TX when device is "level sensitive".
enable drop of control frames which is not needed for regular usage.

So most of this patch set is about TX handling, which is now more complete.
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Signed-off-by: David S. Miller <davem@davemloft.net>