selftests: mlxsw: Add target for router test on spectrum

IPv4 routes in Spectrum are based on the kvd single-hash, but as it's
a hash we need to assume we cannot reach 100% of its capacity.

Add a wrapper that provides us with good/bad target numbers for the
Spectrum ASIC.
Signed-off-by: NYuval Mintz <yuvalm@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
[petrm@mellanox.com: Drop shebang.]
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/drivers/net/mlxsw/spectrum/router_scale.sh

+# SPDX-License-Identifier: GPL-2.0
+source ../router_scale.sh
+
+router_get_target()
+{
+	local should_fail=$1
+	local target
+
+	target=$(devlink_resource_size_get kvd hash_single)
+
+	if [[ $should_fail -eq 0 ]]; then
+		target=$((target * 85 / 100))
+	else
+		target=$((target + 1))
+	fi
+
+	echo $target
+}