net/mlx5e: Don't overwrite pedit action when multiple pedit used

In some case, we may use multiple pedit actions to modify packets.
The command shown as below: the last pedit action is effective.

$ tc filter add dev netdev_rep parent ffff: protocol ip prio 1    \
	flower skip_sw ip_proto icmp dst_ip 3.3.3.3        \
	action pedit ex munge ip dst set 192.168.1.100 pipe    \
	action pedit ex munge eth src set 00:00:00:00:00:01 pipe    \
	action pedit ex munge eth dst set 00:00:00:00:00:02 pipe    \
	action csum ip pipe    \
	action tunnel_key set src_ip 1.1.1.100 dst_ip 1.1.1.200 dst_port 4789 id 100 \
	action mirred egress redirect dev vxlan0

To fix it, we add max_mod_hdr_actions to mlx5e_tc_flow_parse_attr struction,
max_mod_hdr_actions will store the max pedit action number we support and
num_mod_hdr_actions indicates how many pedit action we used, and store all
pedit action to mod_hdr_actions.

Fixes: d79b6df6 ("net/mlx5e: Add parsing of TC pedit actions to HW format")
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>