scylla_setup: fix conditional statement of silent mode

Commit 300af65 introdued a problem in
conditional statement, script will always abort in silent mode, it doesn't
care about the return value.

Fixes #3485

Signed-off-by: Amos Kong <amos@scylladb.com>
Message-Id: <1c12ab04651352964a176368f8ee28f19ae43c68.1528077114.git.amos@scylladb.com>
(cherry picked from commit 364c255)

dist/common/scripts/scylla_setup

@@ -112,13 +112,15 @@ run_setup_script() {
     name=$1
     shift 1
     $* &&:
-    if [ $? -ne 0 ] && [ $INTERACTIVE -eq 1 ]; then
-        printf "${RED}$name setup failed. press any key to continue...${NO_COLOR}\n"
-        read
-        return 1
-    else
-        printf "$name setup failed.\n"
-        exit 1
+    if [ $? -ne 0 ]; then
+        if [ $INTERACTIVE -eq 1 ]; then
+            printf "${RED}$name setup failed. press any key to continue...${NO_COLOR}\n"
+            read
+            return 1
+        else
+            printf "$name setup failed.\n"
+            exit 1
+        fi
     fi
     return 0
 }