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/include/linux/hid.h b/include/linux/hid.h
index 42a0f1d..0a34fb0 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -626,8 +626,8 @@
 	int (*event)(struct hid_device *hdev, struct hid_field *field,
 			struct hid_usage *usage, __s32 value);
 
-	void (*report_fixup)(struct hid_device *hdev, __u8 *buf,
-			unsigned int size);
+	__u8 *(*report_fixup)(struct hid_device *hdev, __u8 *buf,
+			unsigned int *size);
 
 	int (*input_mapping)(struct hid_device *hdev,
 			struct hid_input *hidinput, struct hid_field *field,