Enable optional MD5 hmac cookie generation

configname: CONFIG_SCTP_COOKIE_HMAC_MD5

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>The SCTP Protocol
└─>Enable optional MD5 hmac cookie generation
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Enable optional MD5 hmac based SCTP cookie generation