Revert "net: mirror skb frag ref/unref helpers"

This reverts commit a580ea99.

This revert is to resolve Dragos's report of page_pool leak here:
https://lore.kernel.org/lkml/20240424165646.1625690-2-dtatulea@nvidia.com/



The reverted patch interacts very badly with commit 2cc3aeb5 ("skbuff:
Fix a potential race while recycling page_pool packets"). The reverted
commit hopes that the pp_recycle + is_pp_page variables do not change
between the skb_frag_ref and skb_frag_unref operation. If such a change
occurs, the skb_frag_ref/unref will not operate on the same reference type.
In the case of Dragos's report, the grabbed ref was a pp ref, but the unref
was a page ref, because the pp_recycle setting on the skb was changed.

Attempting to fix this issue on the fly is risky. Lets revert and I hope
to reland this with better understanding and testing to ensure we don't
regress some edge case while streamlining skb reffing.

Fixes: a580ea99 ("net: mirror skb frag ref/unref helpers")
Reported-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Mina Almasry <almasrymina@google.com>
Link: https://lore.kernel.org/r/20240502175423.2456544-1-almasrymina@google.com


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