net: page_pool: create page_pool_alloc_netmem

Create page_pool_alloc_netmem to be the mirror of page_pool_alloc.

This enables drivers that want currently use page_pool_alloc to
transition to netmem by converting the call sites to
page_pool_alloc_netmem.

Signed-off-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20241211212033.1684197-3-almasrymina@google.com


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