HID: allow resizing and replacing report descriptors

Update hid_driver's report_fixup prototype to allow changing report
descriptor size and/or returning completely different report descriptor.
Update existing usage accordingly.

This is to give more freedom in descriptor fixup and to allow having a whole
fixed descriptor in the code for the sake of readability.

Signed-off-by: Nikolai Kondrashov <spbnick@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-prodikeys.c b/drivers/hid/hid-prodikeys.c
index 845f428..48eab84 100644
--- a/drivers/hid/hid-prodikeys.c
+++ b/drivers/hid/hid-prodikeys.c
@@ -740,10 +740,10 @@
 /*
  * PC-MIDI report descriptor for report id is wrong.
  */
-static void pk_report_fixup(struct hid_device *hdev, __u8 *rdesc,
-		unsigned int rsize)
+static __u8 *pk_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
 {
-	if (rsize == 178 &&
+	if (*rsize == 178 &&
 	      rdesc[111] == 0x06 && rdesc[112] == 0x00 &&
 	      rdesc[113] == 0xff) {
 		dev_info(&hdev->dev, "fixing up pc-midi keyboard report "
@@ -751,6 +751,7 @@
 
 		rdesc[144] = 0x18; /* report 4: was 0x10 report count */
 	}
+	return rdesc;
 }
 
 static int pk_input_mapping(struct hid_device *hdev, struct hid_input *hi,