net: Fix double 0x prefix print in SKB dump

When printing netdev features %pNF already takes care of the 0x prefix,
remove the explicit one.

Fixes: 6413139d

 ("skbuff: increase verbosity when dumping skb data")
Signed-off-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>