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>

arch/x86/kernel/setup.c

@@ -1040,8 +1040,6 @@ void __init setup_arch(char **cmdline_p)
 	/* max_low_pfn get updated here */
 	find_low_pfn_range();
 #else
-	num_physpages = max_pfn;
-
 	check_x2apic();
 
 	/* How many end-of-memory variables you have, grandma! */