CHROMIUM: usb: gadget: f_fs: Fix kernel panic for SuperSpeed

Android N adds os_desc_compat in v2_descriptor by init_functionfs()
(system/core/adb/usb_linux_client.cpp) to support automatic
install of MTP driver on Windows for USB device mode.

current __ffs_data_do_os_desc() of f_fs.c will check reserved1 field
and return -EINVAL.
This results in a second adb_write of usb_linux_client.cpp
(system/core/adb/) which doesn't have ss_descriptors filled.
And later kernel_panic (composite.c) occurs when ss_descriptors as
a pointer with NULL is accessed.

Fix is to ignore the checking on reserved1 field so
adb_write goes successfully with v2_descriptor which has
ss_descriptors filled.

BUG=chrome-os-partner:52060
TEST=Connected our device to USB3.0 connector of ubuntu PC
host with USB3.0 cable.

Change-Id: Ib179f982b9ae93fb2fe3b6ac9cd37fb0473235b3
Signed-off_by: Jim Lin <jilin@nvidia.com>
Reviewed-on: https://chromium-review.googlesource.com/340167
Commit-Ready: Jim Lin <jilin@nvidia.com>
Tested-by: Jim Lin <jilin@nvidia.com>
Reviewed-by: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Benson Leung <bleung@chromium.org>
Reviewed-by: Mark Kuo <mkuo@nvidia.com>
(cherry picked from commit 2b0c2bef2a6ab6cd814f5bf4f552cea22f4e5a68)
Reviewed-on: https://chromium-review.googlesource.com/341970
Reviewed-by: Stephen Barber <smbarber@chromium.org>
Commit-Queue: Stephen Barber <smbarber@chromium.org>
Tested-by: Stephen Barber <smbarber@chromium.org>

drivers/usb/gadget/function/f_fs.c

@@ -2062,8 +2062,7 @@ static int __ffs_data_do_os_desc(enum ffs_os_desc_type type,
 		int i;
 
 		if (len < sizeof(*d) ||
-		    d->bFirstInterfaceNumber >= ffs->interfaces_count ||
-		    d->Reserved1)
+		    d->bFirstInterfaceNumber >= ffs->interfaces_count)
 			return -EINVAL;
 		for (i = 0; i < ARRAY_SIZE(d->Reserved2); ++i)
 			if (d->Reserved2[i])