sctp: delete the obsolete code for the host name address param

In the latest RFC9260, the Host Name Address param has been deprecated.
For INIT chunk:

  Note 3: An INIT chunk MUST NOT contain the Host Name Address
  parameter.  The receiver of an INIT chunk containing a Host Name
  Address parameter MUST send an ABORT chunk and MAY include an
  "Unresolvable Address" error cause.

For Supported Address Types:

  The value indicating the Host Name Address parameter MUST NOT be
  used when sending this parameter and MUST be ignored when receiving
  this parameter.

Currently Linux SCTP doesn't really support Host Name Address param,
but only saves some flag and print debug info, which actually won't
even be triggered due to the verification in sctp_verify_param().
This patch is to delete those dead code.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>