mm/vmscan: not necessary to re-init the list for each iteration

node_page_list is defined with LIST_HEAD and be cleaned until
list_empty.

So it is not necessary to re-init it again.

[akpm@linux-foundation.org: remove unneeded braces]
Link: https://lkml.kernel.org/r/20220426021743.21007-1-richard.weiyang@gmail.com


Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>