mlxsw: switchx2: Remove unnecessary conversion to bool

Suppress following warning from coccinelle:

drivers/net/ethernet/mellanox/mlxsw//switchx2.c:183:63-68: WARNING:
conversion to bool not needed here

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>