USB: Add parsing of SuperSpeed endpoint companion descriptor.

Allow the xHCI drivers (and any new USB 3.0 drivers) to parse the
SuperSpeed endpoint companion descriptor to find the maximum number of
bulk endpoint streams the endpoint supports.  This is used to calculate
the maximum total number of streams the driver can allocate.
Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

include/linux/usb/ch9.h

@@ -556,6 +556,8 @@ struct usb_ss_ep_comp_descriptor {
 } __attribute__ ((packed));
 
 #define USB_DT_SS_EP_COMP_SIZE		6
+/* Bits 4:0 of bmAttributes if this is a bulk endpoint */
+#define USB_SS_MAX_STREAMS(p)		(1 << (p & 0x1f))
 
 /*-------------------------------------------------------------------------*/