tls: Fixed a memory leak during socket close

tls: Fixed a memory leak during socket close

During socket close, if there is a open record with tx context, it needs
to be be freed apart from freeing up plaintext and encrypted scatter
lists. This patch frees up the open record if present in tx context.

Also tls_free_both_sg() has been renamed to tls_free_open_rec() to
indicate that the free record in tx context is being freed inside the
function.

Fixes: b574142da9d5 ("net/tls: Add support for async encryption")
Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>