net/mlx5e: Support RSS for IP-in-IP and IPv6 tunneled packets

Add support for inner header RSS on IP-in-IP and IPv6 tunneled packets.

Add rules to the steering table regarding outer IP header, with
IPv4/6->IP-in-IP. Tunneled packets with protocol numbers: 0x4 (IP-in-IP)
and 0x29 (IPv6) are RSS-ed on the inner IP header.
Separate FW dependencies between flow table inner IP capabilities and
GRE offload support. Allowing this feature even if GRE offload is not
supported.  Tested with multi stream TCP traffic tunneled with IPnIP.
Verified that:
Without this patch, only a single RX ring was processing the traffic.
With this patch, multiple RX rings were processing the traffic.
Verified with and without GRE offload support.

Signed-off-by: Aya Levin <ayal@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>