net: script: Fix the net-tools path

Fix the correct path to net-tools directory.
Also default to Bash instead of /bin/sh as we use
Bash syntax.

Signed-off-by: Seppo Takalo <seppo.takalo@nordicsemi.no>

scripts/net/run-sample-tests.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 # Copyright (c) 2019 Intel Corporation
 # SPDX-License-Identifier: Apache-2.0
 
@@ -36,7 +36,7 @@ check_dirs ()
 	    do
 	        local l
 
-	        l="$d/net-tools"
+	        l="$d/tools/net-tools"
 	        if [ -d "$l" ]; then
 		        NET_TOOLS_BASE="$l"
 		        break