This patch enables netifd to query 802.11ac-driver for the maximum
supported A-MPDU length exponent, possibly increasing VHT throughput by
more aggressive frame aggregation.
v2: refreshed patch
Signed-off-by: Matti Laakso <malaakso at elisanet.fi>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@40938 3c298f89-4303-0410-b956-a3cf2f4a3e73