chcr: Handle first or middle part of record

This patch contains handling of first part or middle part of the record.
When we get a middle record, we will fetch few already sent bytes to
make packet start 16 byte aligned.
And if the packet has only the header part, we don't need to send it for
packet encryption, send that packet as a plaintext.

v1->v2:
- un-necessary updating left variable.

v3->v4:
- replaced kfree_skb with dev_kfree_skb_any.

Signed-off-by: Rohit Maheshwari <rohitm@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>