FROMLIST: usb: gadget: f_ncm: allow using NCM in SuperSpeed Plus gadgets.

Currently, enabling f_ncm at SuperSpeed Plus speeds results in an
oops in config_ep_by_speed because ncm_set_alt passes in NULL
ssp_descriptors. Fix this by re-using the SuperSpeed descriptors.
This is safe because usb_assign_descriptors calls
usb_copy_descriptors.

Tested: enabled f_ncm on a dwc3 gadget and 10Gbps link, ran iperf
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Reviewed-by: Maciej Żenczykowski <maze@google.com>
Bug: 162298600
Link: https://lore.kernel.org/linux-usb/20200825055505.765782-4-lorenzo@google.com/


Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ic109e5e83748009ddb1d9445403faa28daba4a70
(cherry picked from commit 06153f72c52b2945eafad9ad83d8dc1321d75fa6)
Signed-off-by: Will McVicker <willmcvicker@google.com>