Add a new flag for AP receive endpoints that indicates whether
a "hard limit" is used as a criterion for closing aggregation.
Add comments explaining the difference between "hard" and "soft"
aggregation limits.

Pass a flag to ipa_aggr_size_kb() so it computes the proper
aggregation size value whether using hard or soft limits.  Move
that function earlier in "ipa_endpoint.c" so it can be used
without a forward-reference.

Update ipa_endpoint_data_valid_one() so it validates endpoints whose
data indicate a hard aggregation limit is used, and so it reports
set aggregation flags for endpoints without aggregation enabled.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>