x86_64: flush_tlb_kernel_range() warning fix

mm/vmalloc.c: In function 'unmap_kernel_range':
mm/vmalloc.c:75: warning: unused variable 'start'

make it a C function so that the compiler thinks it used its arguments.
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

include/asm-x86_64/tlbflush.h

@@ -92,7 +92,11 @@ static inline void flush_tlb_range(struct vm_area_struct * vma, unsigned long st
 
 #endif
 
-#define flush_tlb_kernel_range(start, end) flush_tlb_all()
+static inline void flush_tlb_kernel_range(unsigned long start,
+					unsigned long end)
+{
+	flush_tlb_all();
+}
 
 static inline void flush_tlb_pgtables(struct mm_struct *mm,
 				      unsigned long start, unsigned long end)