USB: Fix off by one in type-specific length check of BOS SSP capability

BugLink: http://bugs.launchpad.net/bugs/1745069

commit 07b9f128 upstream.

USB 3.1 devices are not detected as 3.1 capable since 4.15-rc3 due to a
off by one in commit 81cf4a45 ("USB: core: Add type-specific length
check of BOS descriptors")

It uses USB_DT_USB_SSP_CAP_SIZE() to get SSP capability size which takes
the zero based SSAC as argument, not the actual count of sublink speed
attributes.

USB3 spec 9.6.2.5 says "The number of Sublink Speed Attributes = SSAC + 1."

The type-specific length check patch was added to stable and needs to be
fixed there as well

Fixes: 81cf4a45 ("USB: core: Add type-specific length check of BOS descriptors")
CC: Masakazu Mokuno <masakazu.mokuno@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/usb/core/config.c

@@ -1002,7 +1002,7 @@ int usb_get_bos_descriptor(struct usb_device *dev)
 		case USB_SSP_CAP_TYPE:
 			ssp_cap = (struct usb_ssp_cap_descriptor *)buffer;
 			ssac = (le32_to_cpu(ssp_cap->bmAttributes) &
-				USB_SSP_SUBLINK_SPEED_ATTRIBS) + 1;
+				USB_SSP_SUBLINK_SPEED_ATTRIBS);
 			if (length >= USB_DT_USB_SSP_CAP_SIZE(ssac))
 				dev->bos->ssp_cap = ssp_cap;
 			break;