Stanse found that i2400m_rx frees skb, but still uses skb->len even
though it has skb_len defined. So use skb_len properly in the code.

And also define it unsinged int rather than size_t to solve
compilation warnings.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
Cc: linux-wimax@intel.com
Acked-by: NInaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>