net: mark deliver_skb() as unlikely and not inlined

net: mark deliver_skb() as unlikely and not inlined

deliver_skb() should not be inlined as is it not called
in the fast path.

Add unlikely() clauses giving hints to the compiler about this fact.

Before this patch:

size net/core/dev.o
   text	   data	    bss	    dec	    hex	filename
 121794	  13330	    176	 135300	  21084	net/core/dev.o

__netif_receive_skb_core() size on x86_64 : 4080 bytes.

After:

size net/core/dev.o
  text	   data	    bss	    dec	    hex	filenamee
 120330	  13338	    176	 133844	  20ad4	net/core/dev.o

__netif_receive_skb_core() size on x86_64 : 2781 bytes.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20251103165256.1712169-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>