Added the feature to run an option platform specific script on the fi…

…rst installation.

We added the ability to run an optional platform specific script when the onie image is
installed. This will be useful in the case of doing some switch specifc tasks.

files/image_config/platform/rc.local

@@ -351,6 +351,10 @@ if [ -f $FIRST_BOOT_FILE ]; then
         mv /host/grub.cfg /host/grub/grub.cfg
     fi
 
+    # If there is a platform dependant script, execute it
+    if [ -x /usr/share/sonic/device/${onie_platform}/platform_setup ]; then
+        /usr/share/sonic/device/${onie_platform}/platform_setup
+    fi
     firsttime_exit
 fi