net: Reserve skb headroom and set skb->dev even if using __alloc_skb

When I had inlined __alloc_rx_skb into __netdev_alloc_skb and
__napi_alloc_skb I had overlooked the fact that there was a return in the
__alloc_rx_skb.  As a result we weren't reserving headroom or setting the
skb->dev in certain cases.  This change corrects that by adding a couple of
jump labels to jump to depending on __alloc_skb either succeeding or failing.

Fixes: 9451980a ("net: Use cached copy of pfmemalloc to avoid accessing page")
Reported-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>