net: add sk_drops_skbadd() helper

Existing sk_drops_add() helper is renamed to sk_drops_skbadd().

Add sk_drops_add() and convert sk_drops_inc() to use it.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250826125031.1578842-3-edumazet@google.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>