mm: remove __ARCH_HAS_4LEVEL_HACK and include/asm-generic/4level-fixup.h

There are no architectures that use include/asm-generic/4level-fixup.h
therefore it can be removed along with __ARCH_HAS_4LEVEL_HACK define.

Link: http://lkml.kernel.org/r/1572938135-31886-14-git-send-email-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Anatoly Pugachev <matorola@gmail.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mark Salter <msalter@redhat.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Peter Rosin <peda@axentia.se>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rolf Eike Beer <eike-kernel@sf-tec.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory.c

@@ -4197,19 +4197,11 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
 	smp_wmb(); /* See comment in __pte_alloc */
 
 	ptl = pud_lock(mm, pud);
-#ifndef __ARCH_HAS_4LEVEL_HACK
 	if (!pud_present(*pud)) {
 		mm_inc_nr_pmds(mm);
 		pud_populate(mm, pud, new);
 	} else	/* Another has populated it */
 		pmd_free(mm, new);
-#else
-	if (!pgd_present(*pud)) {
-		mm_inc_nr_pmds(mm);
-		pgd_populate(mm, pud, new);
-	} else /* Another has populated it */
-		pmd_free(mm, new);
-#endif /* __ARCH_HAS_4LEVEL_HACK */
 	spin_unlock(ptl);
 	return 0;
 }