ramdisk_node_list: Add kmsg node

Debugging early loading of pKVM modules is hard. So to make our life a
bit easier, the loader is now redirecting modprobe to /dev/kmsg. Let's
add this node to the initramfs so modprobe can print errors in dmesg.

Bug: 415374827
Change-Id: Ic7e6539e4efebfd9d611b9dd7ee0c29558cd2514