netxen: limit skb frags for non tso packet

Machines are getting deadlock in four node cluster environment.
All nodes are accessing (find /gfs2 -depth -print|cpio -ocv > /dev/null)
200 GB storage on a GFS2 filesystem.
This result in memory fragmentation and driver receives 18 frags for
1448 byte packets.
For non tso packet, fw drops the tx request, if it has >14 frags.

Fixing it by pulling extra frags.

Cc: stable@kernel.org
Signed-off-by: Amit Kumar Salecha <amit.salecha@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>