compat.sh: avoid running duplicate test cases for PSK

With the introduction of PSK_TESTS,
 - Either `compat.sh -V NO` or `compat.sh -V YES` runs the PSK tests
 - `compat.sh` or `compat.sh -V "NO YES"` runs PSK tests only once

Signed-off-by: Yanray Wang <yanray.wang@arm.com>

tests/compat.sh

@@ -1001,10 +1001,20 @@ SKIP_NEXT="NO"
 
 trap cleanup INT TERM HUP
 
-for VERIFY in $VERIFIES; do
+for MODE in $MODES; do
+    PSK_TESTS=""
+    for VERIFY in $VERIFIES; do
         VERIF=$(echo $VERIFY | tr '[:upper:]' '[:lower:]')
-    for MODE in $MODES; do
         for TYPE in $TYPES; do
+
+            if [ "$TYPE" = "PSK" ]; then
+                if [ -z "$PSK_TESTS" ]; then
+                    PSK_TESTS="FINISHED"
+                else
+                    continue;
+                fi
+            fi
+
             for PEER in $PEERS; do
 
             setup_arguments