This is just a small optimization.  The start_pfn can be obtained directly
by phys_index << PFN_SECTION_SHIFT.  So the call of page_to_pfn() is
redundant and remove it.
Signed-off-by: NZhang Zhen <zhenzhang.zhang@huawei.com>
Acked-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Wang Nan <wangnan0@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>