Highmem's realsize always equals to freesize, so it is not necessary to
spare a variable to record this.

Link: http://lkml.kernel.org/r/20180413083859.65888-1-richard.weiyang@gmail.comSigned-off-by: NWei Yang <richard.weiyang@gmail.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>