net: page_pool: rename page_pool_alloc_netmem to *_netmems

page_pool_alloc_netmem (without an s) was the mirror of
page_pool_alloc_pages (with an s), which was confusing.

Rename to page_pool_alloc_netmems so it's the mirror of
page_pool_alloc_pages.

Signed-off-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20241211212033.1684197-2-almasrymina@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>