[kdump]: Parse sonic_platform kernel command line parameter to read t…

…he platform identifier string (sonic-net#1291)

The platform identifier string is used in the reboot script to identify
and execute any custom platform specific reboot script

Signed-off-by: Rajendra Dendukuri <rajendra.dendukuri@broadcom.com>

scripts/reboot

@@ -10,7 +10,7 @@ if [ -e $VMCORE_FILE -a -s $VMCORE_FILE ]; then
         echo "We have a /proc/vmcore, then we just kdump'ed"
         echo "User issued 'kdump' command [User: kdump, Time: ${REBOOT_TIME}]" > ${REBOOT_CAUSE_FILE}
         sync
-        PLATFORM=$(grep -oP 'platform=\K\S+' /proc/cmdline)
+        PLATFORM=$(grep -oP 'sonic_platform=\K\S+' /proc/cmdline)
         if [ ! -z "${PLATFORM}" -a -x ${DEVPATH}/${PLATFORM}/${PLAT_REBOOT} ]; then
             exec ${DEVPATH}/${PLATFORM}/${PLAT_REBOOT}
         fi