cifs: move address comparison into separate function

Move the address comparator out of cifs_find_tcp_session and into a
separate function for cleanliness. Also change the argument to
that function to a "struct sockaddr" pointer. Passing pointers to
sockaddr_storage is a little odd since that struct is generally for
declaring static storage.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>