mm, x86: fix native_pud_clear build error

We still get a build error in random configurations, after this has been
modified a few times:

  In file included from include/linux/mm.h:68:0,
                   from include/linux/suspend.h:8,
                   from arch/x86/kernel/asm-offsets.c:12:
  arch/x86/include/asm/pgtable.h:66:26: error: redefinition of 'native_pud_clear'
   #define pud_clear(pud)   native_pud_clear(pud)

My interpretation is that the build error comes from a typo in
__PAGETABLE_PUD_FOLDED, so fix that typo now, and remove the incorrect
#ifdef around the native_pud_clear definition.

Fixes: 3e761a42e1 ("mm, x86: fix HIGHMEM64 && PARAVIRT build config for native_pud_clear()")
Fixes: a00cc7d9dd ("mm, x86: add support for PUD-sized transparent hugepages")
Link: http://lkml.kernel.org/r/20170314121330.182155-1-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Ackedy-by: Dave Jiang <dave.jiang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/include/asm/pgtable-3level.h

@@ -121,12 +121,9 @@ static inline void native_pmd_clear(pmd_t *pmd)
 	*(tmp + 1) = 0;
 }
 
-#if !defined(CONFIG_SMP) || (defined(CONFIG_HIGHMEM64G) && \
-		defined(CONFIG_PARAVIRT))
 static inline void native_pud_clear(pud_t *pudp)
 {
 }
-#endif
 
 static inline void pud_clear(pud_t *pudp)
 {

arch/x86/include/asm/pgtable.h

@@ -62,7 +62,7 @@ extern struct mm_struct *pgd_page_get_mm(struct page *page);
 # define set_pud(pudp, pud)		native_set_pud(pudp, pud)
 #endif
 
-#ifndef __PAGETABLE_PMD_FOLDED
+#ifndef __PAGETABLE_PUD_FOLDED
 #define pud_clear(pud)			native_pud_clear(pud)
 #endif