net/mlx5e: TC, Fix slab-out-of-bounds in parse_tc_actions

esw_attr is only allocated if namespace is fdb.

BUG: KASAN: slab-out-of-bounds in parse_tc_actions+0xdc6/0x10e0 [mlx5_core]
Write of size 4 at addr ffff88815f185b04 by task tc/2135

CPU: 5 PID: 2135 Comm: tc Not tainted 6.1.0-rc2+ #2
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x57/0x7d
 print_report+0x170/0x471
 ? parse_tc_actions+0xdc6/0x10e0 [mlx5_core]
 kasan_report+0xbc/0xf0
 ? parse_tc_actions+0xdc6/0x10e0 [mlx5_core]
 parse_tc_actions+0xdc6/0x10e0 [mlx5_core]

Fixes: 94d65173

 ("net/mlx5e: TC, Fix cloned flow attr instance dests are not zeroed")
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>