usb: gadget: ffs: add HID descriptor support.

When writing the descriptors to the ep0 file of functionfs, the HID descriptors where not recognized which caused the initialization from user space to fail.
Signed-off-by: Koen Beel <koen.beel@barco.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/f_fs.c

@@ -21,6 +21,7 @@
 #include <linux/blkdev.h>
 #include <linux/pagemap.h>
 #include <linux/export.h>
+#include <linux/hid.h>
 #include <asm/unaligned.h>
 
 #include <linux/usb/composite.h>
@@ -1671,6 +1672,12 @@ static int __must_check ffs_do_desc(char *data, unsigned len,
 	}
 		break;
 
+	case HID_DT_HID:
+		pr_vdebug("hid descriptor\n");
+		if (length != sizeof(struct hid_descriptor))
+			goto inv_length;
+		break;
+
 	case USB_DT_OTG:
 		if (length != sizeof(struct usb_otg_descriptor))
 			goto inv_length;