ARC: thp: unbork !CONFIG_TRANSPARENT_HUGEPAGE build

linux-next for 4.6-rc1 timeline reported ARC build failures !THP

| arch/arc/include/asm/tlbflush.h:29:0: warning: "flush_pmd_tlb_range" redefined [enabled by default]
| arch/arc/include/asm/tlbflush.h:29:0: warning: "flush_pmd_tlb_range" redefined [enabled by default]
| arch/arc/include/asm/tlbflush.h:29:0: warning: "flush_pmd_tlb_range" redefined [enabled by default]

Turns out that commit ("mm/thp/migration: switch from flush_tlb_range
to flush_pmd_tlb_range") triggered the issue while the problem was in
ARC code where THP specific helpers were not guarded with #ifdef.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/tlbflush.h

@@ -17,8 +17,10 @@ void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page);
 void local_flush_tlb_kernel_range(unsigned long start, unsigned long end);
 void local_flush_tlb_range(struct vm_area_struct *vma,
 			   unsigned long start, unsigned long end);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 void local_flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
 			       unsigned long end);
+#endif
 
 #ifndef CONFIG_SMP
 #define flush_tlb_range(vma, s, e)	local_flush_tlb_range(vma, s, e)
@@ -26,7 +28,9 @@ void local_flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
 #define flush_tlb_kernel_range(s, e)	local_flush_tlb_kernel_range(s, e)
 #define flush_tlb_all()			local_flush_tlb_all()
 #define flush_tlb_mm(mm)		local_flush_tlb_mm(mm)
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 #define flush_pmd_tlb_range(vma, s, e)	local_flush_pmd_tlb_range(vma, s, e)
+#endif
 #else
 extern void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 							 unsigned long end);
@@ -34,7 +38,8 @@ extern void flush_tlb_page(struct vm_area_struct *vma, unsigned long page);
 extern void flush_tlb_kernel_range(unsigned long start, unsigned long end);
 extern void flush_tlb_all(void);
 extern void flush_tlb_mm(struct mm_struct *mm);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 extern void flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start, unsigned long end);
-
+#endif
 #endif /* CONFIG_SMP */
 #endif