[syncd.sh] Don't stop sxdkernel during warm shutdown on Mellanox platform (sonic-net#2572)

/etc/init.d/sxdkernel stop may take up to 15 sec which has impact on
control plane downtime

Signed-off-by: Stepan Blyschak <[email protected]>

Author: stepanblyschak

files/scripts/syncd.sh

@@ -155,16 +155,11 @@ stop() {
 
     # platform specific tasks
 
-    # stop mellanox driver regardless of
-    # shutdown type
-    if [ x$sonic_asic_platform == x'mellanox' ]; then
-        /etc/init.d/sxdkernel stop
-        /usr/bin/mst stop
-    fi
-
-
     if [[ x"$WARM_BOOT" != x"true" ]]; then
-        if [ x$sonic_asic_platform == x'cavium' ]; then
+        if [ x$sonic_asic_platform == x'mellanox' ]; then
+            /etc/init.d/sxdkernel stop
+            /usr/bin/mst stop
+        elif [ x$sonic_asic_platform == x'cavium' ]; then
             /etc/init.d/xpnet.sh stop
             /etc/init.d/xpnet.sh start
         fi