selftests: mlxsw: Remove a redundant if statement in tc_flower_scale test

selftests: mlxsw: Remove a redundant if statement in tc_flower_scale test

[ Upstream commit 1f1c92139e36223b89d8140f2b72f75e79baf8bd ]

Currently, the error return code of the failure condition is lost after
using an if statement, so the test doesn't fail when it should.

Remove the if statement that separates the condition and the error code
check, so the test won't always pass.

Fixes: abfce9e062021 ("selftests: mlxsw: Reduce running time using offload indication")
Reported-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Danielle Ratson <danieller@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>