MAINTAINERS: Update page pool entry

Add some file F: matches that is related to page_pool.

Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/r/160613894639.2826716.14635284017814375894.stgit@firesoul
Signed-off-by: Jakub Kicinski <kuba@kernel.org>