[SCTP]: Add check for hmac_algo parameter in sctp_verify_param()

RFC 4890 has the following text:

  The HMAC algorithm based on SHA-1 MUST be supported and
  included in the HMAC-ALGO parameter.

As a result, we need to check in sctp_verify_param() that HMAC_SHA1 is
present in the list.  If not, we should probably treat this as a
protocol violation.

It should also be a protocol violation if the HMAC parameter is empty.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>