x86, mm: Use max_pfn instead of highend_pfn

The 'highend_pfn' variable is always set to 'max_pfn' so just
use the latter directly.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Link: http://lkml.kernel.org/r/1320155902-10424-3-git-send-email-penberg@kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/init_32.c

@@ -683,7 +683,7 @@ static void __init zone_sizes_init(void)
 #endif
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 #ifdef CONFIG_HIGHMEM
-	max_zone_pfns[ZONE_HIGHMEM] = highend_pfn;
+	max_zone_pfns[ZONE_HIGHMEM] = max_pfn;
 #endif
 
 	free_area_init_nodes(max_zone_pfns);