[systemd] Increase syncd startup script timeout to support FW upgrade on init. (#6709)

**- Why I did it**
To support FW upgrade on init.

**- How I did it**
Change timeout value

**- How to verify it**
I manually changed ASIC and Gearbox FW followed by hard reset in order for FW upgrade to take place on init.

Signed-off-by: liora <liora@nvidia.com>

files/build_templates/per_namespace/syncd.service.j2

@@ -26,7 +26,7 @@ ExecStartPre=/usr/local/bin/syncd.sh start{% if multi_instance == 'true' %} %i{%
 ExecStart=/usr/local/bin/syncd.sh wait{% if multi_instance == 'true' %} %i{% endif %}
 ExecStop=/usr/local/bin/syncd.sh stop{% if multi_instance == 'true' %} %i{% endif %}
 {% if sonic_asic_platform == 'mellanox' %}
-TimeoutStartSec=150
+TimeoutStartSec=480
 {% endif %}
 
 [Install]

files/scripts/syncd.sh

@@ -21,9 +21,11 @@ function startplatform() {
             fi
         fi
 
+        debug "Starting Firmware update procedure"
         /usr/bin/mst start --with_i2cdev
         /usr/bin/mlnx-fw-upgrade.sh
         /etc/init.d/sxdkernel start
+        debug "Firmware update procedure ended"
     fi
 
     if [[ x"$WARM_BOOT" != x"true" ]]; then