md: remove the kernel version of md_u.h

mdp_major can just move to drivers/md/md.h.

Signed-off-by: Christoph Hellwig <[e-mail]>
Acked-by: Song Liu <[e-mail]>
Acked-by: Linus Torvalds <[e-mail]>

drivers/md/md.h

···
 		mddev->queue->limits.max_write_zeroes_sectors = 0;
 }
 
+extern int mdp_major;
 void md_autostart_arrays(int part);
 
 #endif /* _MD_MD_H */

include/linux/raid/md_u.h

···
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/*
-   md_u.h : user <=> kernel API between Linux raidtools and RAID drivers
-          Copyright (C) 1998 Ingo Molnar
-	  
-*/
-#ifndef _MD_U_H
-#define _MD_U_H
-
-#include <uapi/linux/raid/md_u.h>
-
-extern int mdp_major;
-#endif