[Dell S6100]: Add dell ich driver (#7336)

dell_ich driver was removed as part of #7309 and it is needed for watchdog tickle in S6100 platform.

platform/broadcom/sonic-platform-modules-dell/s6100/scripts/s6100_platform.sh

@@ -28,6 +28,7 @@ if [[ "$1" == "init" ]]; then
     pericom="/sys/bus/pci/devices/0000:08:00.0"
     modprobe i2c-dev
     modprobe i2c-mux-pca954x force_deselect_on_exit=1
+    modprobe dell_ich
     modprobe dell_s6100_iom_cpld
     modprobe dell_s6100_lpc
     modprobe nvram
@@ -59,6 +60,7 @@ elif [[ "$1" == "deinit" ]]; then
     modprobe -r dell_s6100_iom_cpld
     modprobe -r i2c-mux-pca954x
     modprobe -r i2c-dev
+    modprobe -r dell_ich
     modprobe -r nvram
     remove_python_api_package
 else