x86: Remove pfn in add_one_highpage_init()

commit cc9f7a0c changed
add_one_highpage_init. We don't use pfn any more.
Let's remove unnecessary argument.

This patch doesn't chage function behavior.
This patch is based on v2.6.32-rc5.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
LKML-Reference: <20091022112722.adc8e55c.minchan.kim@barrios-desktop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>