net: mctp: Allow limiting binds to a peer address

net: mctp: Allow limiting binds to a peer address

Prior to calling bind() a program may call connect() on a socket to
restrict to a remote peer address.

Using connect() is the normal mechanism to specify a remote network
peer, so we use that here. In MCTP connect() is only used for bound
sockets - send() is not available for MCTP since a tag must be provided
for each message.

The smctp_type must match between connect() and bind() calls.

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Link: https://patch.msgid.link/20250710-mctp-bind-v4-6-8ec2f6460c56@codeconstruct.com.au
Signed-off-by: Paolo Abeni <pabeni@redhat.com>