x86/headers: Simplify asm/fixmap.h inclusion into asm/pgtable*.h

Instead of including fixmap.h twice in pgtable_32.h and pgtable_64.h,
include it only once, in the common asm/pgtable.h header.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: kasan-dev@googlegroups.com
Cc: kernel-hardening@lists.openwall.com
Cc: linux-mm@kvack.org
Cc: richard.weiyang@gmail.com
Cc: zijun_hu <zijun_hu@htc.com>
Link: http://lkml.kernel.org/r/20170321071725.GA15782@gmail.com
[ Generated this patch from two other patches and wrote changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/pgtable.h

@@ -603,6 +603,7 @@ pte_t *populate_extra_pte(unsigned long vaddr);
 #include <linux/mm_types.h>
 #include <linux/mmdebug.h>
 #include <linux/log2.h>
+#include <asm/fixmap.h>
 
 static inline int pte_none(pte_t pte)
 {

arch/x86/include/asm/pgtable_32.h

@@ -14,7 +14,6 @@
  */
 #ifndef __ASSEMBLY__
 #include <asm/processor.h>
-#include <asm/fixmap.h>
 #include <linux/threads.h>
 #include <asm/paravirt.h>
 

arch/x86/include/asm/pgtable_64.h

@@ -13,7 +13,6 @@
 #include <asm/processor.h>
 #include <linux/bitops.h>
 #include <linux/threads.h>
-#include <asm/fixmap.h>
 
 extern pud_t level3_kernel_pgt[512];
 extern pud_t level3_ident_pgt[512];