IB/core: Add more fields to IPv6 flow specification

Add the following fields to IPv6 flow filter specification:
1. Traffic Class
2. Flow Label
3. Next Header
4. Hop Limit

Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>