mm/x86: prepare for removing num_physpages and simplify mem_init()

Prepare for removing num_physpages and simplify mem_init().

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Jianguo Wu <wujianguo@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 5013a48..c587a87 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -90,7 +90,7 @@
 static void __cpuinit init_amd_k6(struct cpuinfo_x86 *c)
 {
 	u32 l, h;
-	int mbytes = num_physpages >> (20-PAGE_SHIFT);
+	int mbytes = get_num_physpages() >> (20-PAGE_SHIFT);
 
 	if (c->x86_model < 6) {
 		/* Based on AMD doc 20734R - June 2000 */