USB: cdc: add MBIM extended functional descriptor structure

This patch adds the MBIM extended functional descriptor structure
defined in "Universal Serial Bus Communications Class Subclass
Specification for Mobile Broadband Interface Model, Revision 1.0,
Errata-1" published by USB-IF.
Signed-off-by: Ben Chan <benchan@chromium.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/usb/cdc.h

@@ -56,6 +56,7 @@
 #define USB_CDC_OBEX_TYPE		0x15
 #define USB_CDC_NCM_TYPE		0x1a
 #define USB_CDC_MBIM_TYPE		0x1b
+#define USB_CDC_MBIM_EXTENDED_TYPE	0x1c
 
 /* "Header Functional Descriptor" from CDC spec  5.2.3.1 */
 struct usb_cdc_header_desc {
@@ -205,6 +206,17 @@ struct usb_cdc_mbim_desc {
 	__u8    bmNetworkCapabilities;
 } __attribute__ ((packed));
 
+/* "MBIM Extended Functional Descriptor" from CDC MBIM spec 1.0 errata-1 */
+struct usb_cdc_mbim_extended_desc {
+	__u8	bLength;
+	__u8	bDescriptorType;
+	__u8	bDescriptorSubType;
+
+	__le16	bcdMBIMExtendedVersion;
+	__u8	bMaxOutstandingCommandMessages;
+	__le16	wMTU;
+} __attribute__ ((packed));
+
 /*-------------------------------------------------------------------------*/
 
 /*