i40e: FD filters flush policy changes

Since GLQF_FDCNT_0 register now has the right offset, use it to simplify our
FD flush flow.
If the filter add error happens to be for SB we just auto disable SB.

If filter error happens to be for ATR, auto disable ATR and mark
the state to FD_FLUSH_REQUESTED. Which gets cleared when flush completes.

If we are entering flush too quickly (< 30 seconds) and we have quite
a few SB rules, its time to disable ATR for good. Since SB + ATR rules
is most likely making the FD table unstable.

ATR can be re-enabled by turning ntuple off (ethtool -K ntuple off)
and will remain off after turning ntuple on till it gets unstable again.

Change-ID: I2154a2e0a5d44851a2f0eb8731e2f1d4a4d1acbc
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>