[syncd.sh] Clear semaphore before updating firmware (sonic-net#15818)

Why I did it
The hw resources should be released before updating firmware.

How I did it
Added logic to release hw resources in syncd.sh script

Signed-off-by: Vadym Hlushko <vadymh@nvidia.com>

files/scripts/syncd.sh

@@ -2,6 +2,18 @@
 
 . /usr/local/bin/syncd_common.sh
 
+declare -r UNKN_MST="unknown"
+
+function GetMstDevice() {
+    local _MST_DEVICE="$(ls /dev/mst/*_pci_cr0 2>&1)"
+
+    if [[ ! -c "${_MST_DEVICE}" ]]; then
+        echo "${UNKN_MST}"
+    else
+        echo "${_MST_DEVICE}"
+    fi
+}
+
 function startplatform() {
 
     # platform specific tasks
@@ -23,6 +35,12 @@ function startplatform() {
 
         debug "Starting Firmware update procedure"
         /usr/bin/mst start --with_i2cdev
+
+        local -r _MST_DEVICE="$(GetMstDevice)"
+        if [[ "${_MST_DEVICE}" != "${UNKN_MST}" ]]; then
+            /usr/bin/flint -d $_MST_DEVICE --clear_semaphore
+        fi
+
         /usr/bin/mlnx-fw-upgrade.sh
         /etc/init.d/sxdkernel restart
         debug "Firmware update procedure ended"