mlxsw: spectrum_buffers: Set a minimum quota for CPU port traffic

mlxsw: spectrum_buffers: Set a minimum quota for CPU port traffic

In commit 19e2a40252c5 ("mlxsw: spectrum: Allow packets to be trapped
from any PG") I fixed a problem where packets could not be trapped to
the CPU due to exceeded shared buffer quotas. The mentioned commit
explains the problem in detail.

The problem was fixed by assigning a minimum quota for the CPU port and
the traffic class used for scheduling traffic to the CPU.

However, commit b4b0ff427e74 ("mlxsw: Create a different trap group list
for each device") assigned different traffic classes to different
packet types and rendered the fix useless.

Fix the problem by assigning a minimum quota for the CPU port and all
the traffic classes that are currently in use.

Fixes: b4b0ff427e74 ("mlxsw: Create a different trap group list for each device")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Eddie Shklaer <eddies@mellanox.com>
Tested-by: Eddie Shklaer <eddies@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>