net: suppress warnings on dev_alloc_skb

Noticed an allocation failure in a network driver the other day on a 32 bit
system:

DMA-API: debugging out of memory - disabling
bnx2fc: adapter_lookup: hba NULL
lldpad: page allocation failure. order:0, mode:0x4120
Pid: 4556, comm: lldpad Not tainted 2.6.32-639.el6.i686.debug #1
Call Trace:
 [<c08a4086>] ? printk+0x19/0x23
 [<c05166a4>] ? __alloc_pages_nodemask+0x664/0x830
 [<c0649d02>] ? free_object+0x82/0xa0
 [<fb4e2c9b>] ? ixgbe_alloc_rx_buffers+0x10b/0x1d0 [ixgbe]
 [<fb4e2fff>] ? ixgbe_configure_rx_ring+0x29f/0x420 [ixgbe]
 [<fb4e228c>] ? ixgbe_configure_tx_ring+0x15c/0x220 [ixgbe]
 [<fb4e3709>] ? ixgbe_configure+0x589/0xc00 [ixgbe]
 [<fb4e7be7>] ? ixgbe_open+0xa7/0x5c0 [ixgbe]
 [<fb503ce6>] ? ixgbe_init_interrupt_scheme+0x5b6/0x970 [ixgbe]
 [<fb4e8e54>] ? ixgbe_setup_tc+0x1a4/0x260 [ixgbe]
 [<fb505a9f>] ? ixgbe_dcbnl_set_state+0x7f/0x90 [ixgbe]
 [<c088d80d>] ? dcb_doit+0x10ed/0x16d0
...

Thought that perhaps the big splat in the logs wasn't really necessecary, as
all call sites for dev_alloc_skb:

a) check the return code for the function

and

b) either print their own error message or have a recovery path that makes the
warning moot.

Fix it by modifying dev_alloc_pages to pass __GFP_NOWARN as a gfp flag to
suppress the warning

applies to the net tree

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Alexander Duyck <alexander.duyck@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -2467,7 +2467,7 @@ static inline struct page *__dev_alloc_pages(gfp_t gfp_mask,
 
 static inline struct page *dev_alloc_pages(unsigned int order)
 {
-	return __dev_alloc_pages(GFP_ATOMIC, order);
+	return __dev_alloc_pages(GFP_ATOMIC | __GFP_NOWARN, order);
 }
 
 /**
@@ -2485,7 +2485,7 @@ static inline struct page *__dev_alloc_page(gfp_t gfp_mask)
 
 static inline struct page *dev_alloc_page(void)
 {
-	return __dev_alloc_page(GFP_ATOMIC);
+	return dev_alloc_pages(0);
 }
 
 /**