staging: octeon: Fix build failure due to typo.

drivers/staging/octeon/ethernet-tx.c:287:23: error: implicit declaration of function 'skb_drag_size'; did you mean 'skb_frag_size'? [-Werror=implicit-function-declaration]

From kernelci report:

	https://kernelci.org/build/id/5d3943f859b514103f688918/logs/

Fixes: 92493a2f ("Build fixes for skb_frag_size conversion")
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/staging/octeon/ethernet-tx.c

@@ -284,7 +284,7 @@ int cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
 
 			hw_buffer.s.addr =
 				XKPHYS_TO_PHYS((u64)skb_frag_address(fs));
-			hw_buffer.s.size = skb_drag_size(fs);
+			hw_buffer.s.size = skb_frag_size(fs);
 			CVM_OCT_SKB_CB(skb)[i + 1] = hw_buffer.u64;
 		}
 		hw_buffer.s.addr = XKPHYS_TO_PHYS((u64)CVM_OCT_SKB_CB(skb));