FROMLIST: usb: gadget: f_ncm: set SuperSpeed bulk descriptor bMaxBurst to 15

This improves performance on fast connections. When directly
connecting to a Linux laptop running 5.6, single-stream iperf3
goes from ~1.7Gbps to ~2.3Gbps out, and from ~620Mbps to ~720Mbps
in.

Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Bug: 162298600
Link: https://lore.kernel.org/linux-usb/20200825055505.765782-3-lorenzo@google.com/


Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I1046dee7020da04b773ee6bbf8e5fbecde506df7
(cherry picked from commit f6ff78ab9bce19d30086b4285c61bf9239a0811c)
Signed-off-by: Will McVicker <willmcvicker@google.com>